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The coastal dune fields studied

At present there are only six large open dune fields (over 50 ha) on the coasts of Finland: Vattaja, Tauvo, Yyteri, the west coast of Hailuoto, Kalajoki and Monäs (in order of size; Fig. 3), the last of which has been invaded by pine forest during the last ten years and can no longer be said to belong to this group. These sites have more dunes hidden in the forest landwards of the open sandy fields, but they are older, stabilized and have lost their connection with the present-day beach zone. There are often wet depressions between the old dunes and the beach, the oldest of them having turned into peat bogs. The areas quoted for these coasts include only the open beach, dune meadow and heath, so that all of the dunefields are much larger than the figure given here would suggest. The numbering of the coasts refers to Figure 3.

 

Coasts of the Gulf of Finland

There are many sandy shores on the Gulf of Finland, e.g. near Porvoo, but no aeolian sand worth mentioning. The reasons for this are the shelter afforded by the islands and the coarse, poorly sorted material of these beaches.

 

1. Hyypiä, Virolahti (4 ha)

This coast (Fig. 3, nr. 1) is sheltered by some small islands. The shore is stony and the beach is interrupted by rocky promontories. Aeolian sand has accumulated at embayments in places where southerly winds are able to blow at their full strength between the islands. The soil in this region is sandy (Geological Map of Finland 1981), and forest begins immediately landward of the beach. The dunes are low, under 2 m, and bound by vegetation, the highest ones being covered by forest. Aeolian activity on this coast is restricted at present to deflation. A large number of summer cottages have been built on the beach during the last twenty years.

 

Coasts of the Hanko Peninsula

The Hanko Peninsula is part of a large ice marginal formation (end moraine), the First Salpausselkä (Fig. 3), containing mainly glaciofluvial sand and gravel. The winds affecting the shores of the Hanko Peninsula nowadays have mainly an eroding action, but sand is also accumulating to form beach ridges and tombolos. Small, sandy embayments opening out to the south are bordered by dunes. The dunes on the distal slopes of the end moraine are usually small, though there is plenty of well sorted fine sand on these slopes, but one can find higher, stabilized dunes on the top. The winds blowing from the south and south-east are most effective on these beaches.

2. Lappohja (7 ha)

The embayment of Lappohja (Fig. 3) opens out to the south-east and is bordered by the steep slope of the First Salpausselkä (Fig. 4). The inclination of the slope is over 10o in places. Longshore bars and beach ridges lie on a cut-and-built terrace in the littoral zone. Only the beach and the trampled slopes are unvegetated. The material is poorly sorted in some places and includes some boulders. Deflation has caused an enrichment of coarse material on the surface. The fine, well sorted dune sand, differing markedly from this material, cover the slope in the middle part of the embayment. The beach profile changes seasonally the slope being steeper in spring, after the winter storms and high water levels, while aeolian sand accumulates on the parallel beach ridges later in the summer, during the period of low water.

Fig. 4. The Lappohja beach (Hanko; no. 2 in Fig. 3) and a profile across the deflated part of it on 26 July 1987.

Comparing the Basic Maps of 1952 and 1982, it seems that the shoreline and the beach have remained about the same for decades. Many southern plants and animals such as Ammophila arenaria, Carex arenaria, Aegialia arenaria and Lasius meridionalis (Veikkolainen 1995), which are rare in Finland, are found on this shore. This area was purchased for recreational use in summer 1995. It belongs both to the esker and coastal protection programmes, which means that no substantial building is allowed. The Ammophila population has survived at least from the 1930's (Lemberg 1935: 44), although it is no longer as abundant as it was then. Viola canina and Thymus serpyllum were also more common in the 1930's.  

3. Syndalen (2 ha)

This coast (Fig. 3, nr. 3) belongs to a military area, and a barracks has been built on the shore. Comparing the present day landscape with the photographs taken by Lemberg 1923 (Lemberg 1933: app. 7, 1935: app. 2), it can be seen that the vegetation cover has increased quite markedly. The vast, open sand fields in the photographs have now disappeared, as also has the dune vegetation. Trampling has kept the dune slope around the barracks free of vegetation, and Carex arenaria is still growing there, although the large stands described by Lemberg (1935: 45) have disappeared. C. arenaria cannot survive in thick grass.

According to Lemberg (1935: 45), Agrostis stolonifera, Juncus bufonius, Gnaphalium uliginosum, Eleocharis acicularis and Honkenya peploides were also frequent on this beach. The last-mentioned is still growing there, but the other species may reflect shoaling and eutrophication of the beach, which must have preceded the invasion of the reedbed.  

4. Henriksberg

A sandy tombolo connects a rocky islet to the mainland (Fig. 3, nr. 4). Foredunes bound by lyme-grass line the embayment east of the tombolo, and the wind has also caused sand to drift onto the cliffs.  

5. Vedagrundet

The tombolo of Vedagrundet (Fig. 3, nr. 5) is wider, and a foredune has accumulated on its SW shore. The beach seems to be broader on the map of 1982 than on that of 1966, possibly due to the increased use of this area for swimming. The vegetation cover includes many colourful wild flowers. Cakile maritima is frequent on the beach, while the lichen-rich meadow behind the Leymus arenaria dunes includes Epilobium angustifolium, Hieracium umbellatum, Rhinanthus serotinus and Galium verum.  

6. Kolaviken, Hanko (6 ha)

This is a popular swimming beach in the town of Hanko (Fig. 3). The beach face features a low ridge, a berm covered with aeolian sand. In some places on this ridge Rosa rugosa is dominant as a weed. A sparse pine forest grows landwards of this, covering hummock dunes where low shrubs, mosses and lichens grow in patches on the trampled sand surface. Ants bring fine sand to the surface. As compared with the records of Lemberg (1935: 50), R. rugosa, Artemisia vulgaris and Tanacetum vulgare seem to be more frequent nowadays and Sedum acre less so.  

7. Tulliniemi, Hanko (17 ha)

The First Salpausselkä extends to Tulliniemi (Fig. 3). This tip of the peninsula was formed, as a tombolo, only at the end of the seventeenth century (Keynäs et al. 1993). The arcuate beach, more than one kilometre long, faces south-east. Data from the meteorological station on the island of Russarö, just off the peninsula, indicate that easterly winds are frequent in spring and severe winter storms often blow from the south (Table 2). The grain size of the material accumulating on the beach varies with the power of the waves, with fine sand accumulating in calm periods, usually in the summer. In summer 1987, for example, there was a 20 cm high berm of very fine, well sorted material. When there are strong winds, fine sand is washed seaward and the accumulations on the beach consist of coarse gravel. Cusps of gravel about 0.4 m high can be seen in Figure 5. Since autumn 1994 the shore has been eroded by high winds and the proximal slope of the foredune has retreated about one metre landward. At the same time the foredune has grown about 0.5 m higher.

Festuca polesica is already common on the leeward slope of the foredune (Fig. 6) and there are numerous hummock dunes about 0.5 m high under the pines, and the bases of the pines are often buried in sand. Before the present-day fire protection measures came into force, the dry vegetative cover was occasionally destroyed by fire, so that the sand drifted into a dune ridge 3.5 m high. The oldest, partly buried, pines in this area are already over 200 years old (Keynäs et al. 1993: 13-14).

Fig. 6. A profile across the open beach of Tulliniemi (Hanko; no. 7 in Fig. 3) on 26 July 1978. Measurements of soil nutrient content are shown under the profile (four samples).

Festuca polesica and Carex arenaria are rare in Finland other than on the Hanko Peninsula, and Sphingonotus coerulans and Phimodera humeralis are insects that live in Finland only on the sandy F. polesica meadows of this peninsula (Keynäs et al. 1993: 19). Carex arenaria is frequent in the northern part of Tulliniemi. Salsola kali, classified as an endangered species in Finland, was to be found on most beaches of the Hanko Peninsula at the beginning of this century, after which it disappeared in the 1940's, but it returned in the early 1980's and nowadays forms a population of hundreds, sometimes thousands of individuals on the shores of Tulliniemi (Keynäs et al. 1993: 19). The occurrence of Salsola kali seems to follow the variation in annual mean temperatures. Thymus serpyllum var. ericoides and Coelocaulon aculeatum subsp. aculeatum are rare coastal variants with a south-westerly distribution. Thus the southerly location of Tulliniemi affects the fauna and flora of the area.

 

Coasts of the southwestern archipelago

In this area the coasts are often rocky and sheltered by numerous islands. The acidic bedrock is interspersed with local occurrences of limestone.  

8. Padva, Tenhola (6 ha)

This sandy isthmus is a part of a NW-SE esker chain lying distally to the Second Salpausselkä end moraine (Fig. 3, nr. 8). The beach is open to southerly and southwesterly winds. The winds and waves have piled up a low beach ridge, and landward of this there is a deflation surface with some small hummock dunes. Further landward the forest covers higher, parallel dune ridges which were formed at a time when the shoreline was advancing because of land uplift and the wind was accumulating sand on the ridges. There are summer cottages on the northwestern part of the beach, but trampling has not been very intensive around them. The southeastern part is used for swimming and camping, and is harrowed every spring. The pine forest behind the bathing beach has been heavily trampled.

The sand of the Padva beach contains calcium, which is rapidly leached from the topsoil further away from the shoreline, leaving the soil acid (Fig. 7). This calcium, accumulated by the waves, may originate from the local glacial till, as limestone is found about ten kilometres northwest of Padva (Geological Map of Finland 1955), and there may be more in the sea bottom.

 

Fig. 7. A profile across the unharrowed part of the Padva beach (Tenhola; no. 8 in Fig. 3) on 29 August 1987. Measurements of soil nutrient content are shown under the profile (three samples).

 

Coasts of the Bothnian Sea

The beaches of Yyteri are located on the Jotnian sandstones (Tikkanen 1981: 259). Weathering, and particularly the glaciations, separated out large amounts of fine sand suitable for aeolian transport from the sandstone, and the glacial meltwaters accumulated this material into an large esker chain extending over 70 km from Virttaankangas to Yyteri (Tikkanen 1981: 285) and further as a submarine esker of unusually large dimensions (Winterhalter 1972: 42). Beach drift, waves and winds have deposited sand onto the shores of Yyteri. Only the most resistant mineral is left in appreciable amounts. The sand of Yyteri is quite pure quartz sand, with some mica in the fine fractions. The beaches lie south of Mäntyluoto, the harbour of Pori.  

9. Yyterinsannat, Pori (100 ha)

The arcuate beach of Yyterinsannat (Fig. 3, nr. 9) extends three kilometres northwards from the tombolo of Munakari, and there is also a spit reaching almost three kilometres south from the tombolo. Pebbles and cobbles have been enriched on this mainly submerged tombolo by powerful wave action. At the northern edge of Yyterinsannat lies the headland of Herrainpäivät and to the north of this there are two more smaller beaches (Fig. 8). Numerous old, stabilized, forested dunes are to be found landward of Yyterinsannat and separated from it by a broad depression that lies almost at the sea level and is used for camping, parking, rented cottages and other buildings. A hotel and a restaurant have been built on the top of the highest dune ridge, which borders onto the landward edge of the Yyterinsannat dune field, and there is a holiday village in the southern part of Yyterinsannat. The area between the hotel and the restaurant is the most heavily trampled. There is also a small amusement park, and two deflation basins have been deepened to form a swimming pool, the water level of which varies with the sea level. The foredune has been activated by strong winds in the most trampled places over the past few years (Fig. 9).

Fig. 8. Aerial photograph (no. 9519:112) of the Yyteri dune field (Pori; no. 9-11 in Fig. 3) in 1995. Compare with figure 9. By permission of © Maanmittauslaitos, permit no. 51/MML/08.

Fig. 9. At Yyterinsannat (Pori; no. 9 in Fig. 3) the foredune has become mobile at the most severely trampled sites during the 1990's and active slipfaces have formed (photographed on 7 July 1996).

The meteorological station of Kuuskajaskari lies almost 50 km south of Yyteri, but both of these places are similarly exposed to winds. The most significant winds seem to blow from between south and west, varying with the season (Table 2). When NW winds prevail, the headland of Herrainpäivät shelters the northernmost part of the beach, and this area was connected to the mainland by a tombolo in the eighteenth century (Wahlroos 1890; Wallin 1980: 6-8). This isthmus is still marked as a coastal sand flat on Häyrén's map published in 1909 (Fig. 10).

Fig. 10. The Yyteri dune field at the beginning of this century, drawn after Häyrén (1909: map appendix). The area to the north of Karhuluoto was still under water.

Southerly and southwesterly winds are most effective in the northern part of the beach, while the waves are broken by Munakari in the south. The waves refract around the tombolo and move the sediment towards it. The shoals are much broader to the north of the tombolo than to the south. The foredune alters in its morphology with the sediment supply. In the southern part of Yyterinsannat the sediment budget is positive, the slope profile is gentle with numerous longshore bars and the foredunes are low, parallel ridges of height 0.5-2 m on the prograding beach (Fig. 11). South of the holiday village the dune ridges have grown together to form one ridge 3-5 m high. These dune ridges consist of concentric layers, and the windward slopes also show aeolian cross-bedding. The small, terrace-like embryo dunes on the windward slopes are bound by Honkenya peploides in some places.

Fig. 11. Profiles across the parallel dune ridges in the southern part of Yyterinsannat (Pori): (A) on 10 July 1987 after a long period of uninterrupted development.

(B) the same place on 7 July 1991 after severe autumnal storms. Measurements of soil nutrient content are shown under the profile (three samples). The location of the profiles is shown by (a) in Figure 13.

The slopes of the foredunes have a gradient of 5-10o (Tikkanen 1981: 306), but can reach 30-35o in some places on the leeward slopes. The foredune ridge is at its highest in the middle part of the beach, at the restaurant, where it reaches about 8 m and the slopes are steeper than in the south. From here to the northern part of the beach the windward slopes are steeper than the leeward slopes (average 30o), because of wave erosion, deflation and trampling, except in places where the dune is actively moving and a slipface has developed. Elsewhere the leeward slopes consist of blowover strata. Because of the severe trampling, the foredune ridge is broken by numerous wind-scoured blowouts. The windward slopes on the northern part of the beach are characterized by slumped tufts of lyme-grass (Fig. 12) and there are trees growing on the dune. The foredune is again lower in its northernmost part, 1.5-2 m, and the windward slopes are steeply eroded by waves (Fig. 13). The shoreline in this area has remained almost unchanged since the beginning of this century (Wallin 1980), but the dune slope has retreated as a result of storms over the past few years.

Fig. 12. The windward slopes of the foredune near the hotel and the restaurant at Yyterinsannat (see Fig. 13) are characterized by slumped tufts of lyme-grass. Strong winds erode the bare slopes in winter and the waves can reach the toe of the dune during severe autumnal storms. In the photograph, taken on 13 March 1994, the sea is covered by ice and there are snow patches on the beach.

Fig. 13. A profile across the northernmost part of the Yyterinsannat dune field (Pori; no. 9 in Fig. 3) on 8 June 1988. Periodic wave attacks have undercut the old foredune. The location of the profile is shown by (b) on the map of Yyterinsannat.

Thus all the topography types of the Irish dunes proposed by Carter (1990, see Fig. 1) can be seen in Yyteri. The shoreline in the southern part of the beach is prograding quite fast, assisted by the beach drift, while the sediment budget in the middle part is more balanced and there are avalanche and slump layers on the windward slopes of the foredune. Here the dunes have had time to grow to some height. In the nothern part the waves have eroded the foredune and its leeward slopes are covered by blowover layers. These layers are also formed by niveo-aeolian deposition in winter.

Deflation, assisted by trampling, has moulded bowls as much as three metres deep behind the foredune, some of which have reached the groundwater level and are distinguishable from a distance as dark spots, being covered by mosses. Others, with dry, sandy bottoms, are still deepening (Fig. 14). The deflation bowls are covered by ice in winter. There are erosion remnants with more or less even summits to be found between the deflation bowls in some places (cf. Van Dieren 1934: 207; Seppälä 1974: 218), having grown higher as sand originating from the deflation bowls has accumulated amongst the vegetation.

Fig. 14. An active deflation bowl between the foredune and the holiday village at Yyterinsannat (Pori; no. 9 in Fig. 3) on 9 June 1988. Thick layers of cover and sand have accumulated landward of it.

The highest dune of Yyterinsannat lies landward of this undulating terrain, 100 m from the shoreline in the north and 500 m from it near the holiday village. The highest point of this formation, which is more than 2 km long, called Keisarinpankki, reaches about 20 m above sea level. This high dune is asymmetrical in cross-section, with a gradient of 10-20o on the windward slope and as much as 30-45o in places on the leeward slope (Tikkanen 1981: 306). It seems that this dune has not moved much from its original position, although deflation of the windward slopes has made it more sinuous. There are some deep deflation bowls located proximally to it, but no continuous deflation surfaces. This high dune was already well established in its present location and at its present height in year 1907 (Wallin 1980: 8), and no buried soil layers have been found under it in drilling (Tikkanen, oral communication 1993). The growth of this dune has been assisted by the forest growing in the humid depression leeward of it, as the trees and bushes have weakened the power of wind and the sand grains have been deposited on the dune ridge (cf. Heikkinen 1994: 272). The trees growing on the dune have been partly buried in the sand, whereas the roots of some pines on the windward slope have been exposed by deflation. This dune is no longer growing, as the younger dunes trap the sand nearer the shoreline. Even the windward slope has mainly been stabilized by vegetation in spite of trampling, and also downhill skiing in winter. The exceptionally high, steep leeward slope is covered by a dense patch of mesic, herb-rich forest (Fig. 15), the efficient sand binding capacity of which contributes to the steepness of the slope. The great contrast between the vegetation of the sunny, windy SW slope and the shady, leeward NE slope is due to these microclimatological differences.

Fig. 15. The exceptionally steep leeward slope of the Keisarinpankki dune (Yyterinsannat, Pori; see Fig. 13) is covered by a dense patch of mesic, herb-rich forest (photographed on 26 July 1990).

According to Wallin (1980), the Yyteri area rose above the sea level in the 6th century AD. The highest rate of shoreline displacement was about 5 m in a year. The present beach began to form in the 18th century. At the beginning of this century Yyterinsannat was an open sand field, and some islands had just been connected to it (Suomenmaa 1906: 301-302). In the photographs taken by Lemberg (1933: app. 1) the foredune lying at the present shoreline has already began to form. At that time there was a dune ridge 1.5 m high and 20 m broad bound by Honkenya peploides and the sand field was smooth compared with the modern landscape and covered mainly by Festuca rubra (Lemberg 1935: 54), which has subsequently declined, to be replaced by Deschampsia flexuosa. The deflation bowls have grown deeper and the hummock dunes larger. Where Lemberg (1935: 55) records that some damp deflation surfaces were covered by an algal crust, they are nowadays covered by mosses. No extensive dark areas indicative of a moss cover can yet be seen on aerial photographs taken in the 1970's.  

10. The Herrainpäivät area, Yyteri, Pori (25 ha)

The area of Herrainpäivät is taken here to denote the sand field between the headlands of Herrainpäivät and Karhuluoto (Fig. 3, nr. 10). Lemberg (1935: 58) describes this sandy isthmus at the beginning of this century as follows: 'In the NW part of the sand field there was a Calamagrostis epigejos dune 0.5 m high bordering on the forest of Karhuluoto. The alders in the south were surrounded by a drift sand field. In the SW part the trees at the forest edge had led to the accumulation of a dune 4-5 high, the sand on the leeward slope of which had slipped down onto an older dune bound by Juniperus communis, as a result of which the bushes had died.' All these dunes are still distinguishable, but are now covered by forest.

The profile of the beach face is steeper here than in the Yyterinsannat area. The foredune reaches about 6 m above sea level and follows the north-south direction of the shoreline. It receives its sand from the gently sloping beach, which is 50 m in width. The foredune has grown quickly, since it must have reached the necessary height some time between the mappings of 1977 and 1987 (aerial photographs of 1974 and 1983, contour intervals 2.5 m). The beach also seems to have grown about 40 m broader during this same interval, and the shoals in front of the beach narrowed by the same amount. On the zoning map of Pori dating from 1979 (scale 1:2000, contour intervals 0.5 m) the highest points of the dune already reach 4 m above sea level. Honkenya peploides and Leymus arenarius bind individual hummock dunes on the beach, and Honkenya also forms 'terraces' on the windward slope (Fig. 16). The dune rises 5 m above the beach. The windward slope has an average gradient of 10o. The leeward slope is shorter and its gradient varies considerably. Its relative height was about 2 m in 1987 and about 4 m in 1995. The dune seems to have increased in height by more than 20 cm a year over the past few years.

Fig. 16. Honkenya peploides binds hummock dunes on the beach and 'terraces' on the windward slope of the foredune in the area of Herrainpäivät (Pori; no. 10 in Fig. 3). Photographed on 26 July 1990.

The lengthwise sand ridges on the southern part of the beach are separated by wind-scoured blowouts. The sand supply on this part of the 500 m long beach is very abundant at times of strong NW winds, which can blow obliquely over it (cf. Nordstrom & Jackson 1993). Wind transports sand up the gaps until the walls prove to be over-steepened and small avalanches are formed under gravity. Strong winds moving sand up the gaps fashion sharp crests on these ridges (Fig. 17). The form of these ridges is due to the interaction of turbulent wind, deposition of sand, the vegetation cover and trampling.

Fig. 17. Strong northerly winds have moulded elongated dune ridges separated by wind-scoured blow-outs near the headland of Herrainpäivät (Pori; no. 10 in Fig. 3). Photographed on 9 June 1988.

Landward of the foredune there is a gently undulating sand field, the grain-size distribution of the material of which is quite similar to that of the foredune, but with slightly more coarse grains. This area is now being invaded by pine forest.  

11. The Karhuluoto area, Yyteri, Pori (15 ha)

The Karhuluoto area (Fig. 3, nr. 11) denotes here the sand field between the headlands of Karhuluoto and Mäntyluoto. In the 1930's this was an even, expanding sand flat (Lemberg 1935: 57). Thus its oldest dunes were formed after that time. The beach is sheltered by the foreland of Uniluoto, and the waves are broken up by broad shoals in front of the beach. Comparing the Basic Maps of 1970 and 1987, the shoreline seems to have advanced only 10 m, but the shoals have expanded seaward by as much as 120 m.

There was a low, discontinuous embryo dune ridge only 10-20 cm high in the middle part of the beach in summer 1987, but lyme-grass was already growing on it densely by the next summer and the dune was 0.5 m high and continuous (Fig. 18). There were two parallel dune ridges 1-2 m high, landward of it, the one lying closer to the shore in particular being interrupted by wind-scoured gaps. Some long (8 m), low (10 cm) fan-like blowover 'deltas' formed to the lee of these ridges. The third, furthest parallel dune ridge had broken into separate mounds bound by sterile lyme-grass (Fig. 19), and these dune mounds continued for over 40 m, becoming lower further away from the shoreline. These mounds had numerous open sandy surfaces smoothed by rains and winds and dotted by dark sand 'lumps' formed by fungal hyphae (Fig. 20). The sand in the more humid depressions was covered by an algal crust (Cyanobacteria). Cover sand had accumulated landward of the dune mounds.

Fig. 18 A 0,5 m high dune ridge (in the upper righthand corner), which is here two years old (on 9 June 1988), is bound by lyme-grass. The stands of Phragmites australis (seaward of the ridge) later formed part of a newer, parallel foredune. The tufts of lyme-grass in the foreground are growing on a dune ridge 2 m high. The headland of Karhuluoto (Pori; no. 11 in Fig. 11) is in the background.

Fig. 19. Water erosion and deflation have broken old dune ridges into separate sand mounds bound by sterile lyme-grass, mosses and lichens (Karhuluoto area, Pori; no. 11 in Fig. 3). Photographed on 9 June 1988.

Fig. 20. Dark sand 'lumps', formed by fungal hyphae binding sand grains together on bare deflation surfaces (Karhuluoto area, Pori; no. 11 in Fig. 3). The 'lumps' are usually about 3 cm in diameter (photographed on 9 June 1988).

The landscape was completely changed in spring 1990, when the dune field was levelled to form a golf-course. The embryo dune had developed into a foredune by that time, and in summer 1995 it was 1.5 m high and partly bound by Phragmites australis. The dredging that has taken place near this area does not seem to have reduced the supply of sand to the beaches of Yyteri.

All the sand samples taken from the Karhuluoto area have a the median grain size finer than 0.2 mm. Finer and coarser layers can be seen on the shore, and the samples, including those representing the coarser part of the grain-size distribution, contain a large number of dark mica scales that may originate from the till of the headlands. In some places on the beach the fine sand forms a crust that protects the surface from deflation. This crust is nevertheless broken by trampling, but is promoted by all forms of impurity such as algae, salts and pollutants. Pollution of the air and water has been greatly increased by the chemicals factory at Mäntyluoto (Atlas of Finland 1986: folio 132: 11). The fine sand can also be bound by the humidity that prevails after long periods of rain.

 

Coasts of the Quark

There are many dune fields on the coasts of the Quark and the Bothnian Bay, and even the till in this area contains large proportions of sand and silt (Okko 1949: 31-33). During the glaciations material was transported here from the deeps in the Gulf of Bothnia, which also contain sandstone (Okko 1949: 37; Atlas of Finland 1990: folio 124: 24), and sand has also been carried to the coast by streams and rivers. Land uplift has been up to 1 m in a century this area, and this has assisted in the formation of dune fields, as the sand flats that become exposed continuously provide new material for aeolian transport.  

12. Storsanden, Monäs (50 ha)

Storsanden is situated on the northern tip of the Monäs Peninsula, near the town of Nykarleby (Fig. 3). There is only one foredune bordering on the two kilometres of beach, and this becomes lower fom west (2.5 m) to east (1 m). Its windward slope has been eroded by waves and is steep, up to 30o in places, while the leeward slope consists of blowover layers. A sandy tombolo in the middle part of the beach connects the island of Lotan to the mainland (Fig. 21).

Fig. 21. An aerial photograph of Storsanden (Monäs, Nykarleby; no. 12 in Fig. 3) on 12 June 1955 (top; no. 5555:43) and on 12 May 1990 (bottom; no. 90154:34). In spite of shoreline displacement, the open white sandy field has narrowed. It is covered by mosses and the forest edge has advanced. The older dunes have also gained a forest cover. The tracks left by motorcycles can be seen clearly. The sand bars have grown larger and the ponds in the lower part of the older photograph have been filled in to form peat bogs. A tombolo connects the mainland to the island of Lotan. The waterway in the east is an elongated bay called Monässundet. By permission of © Maanmittauslaitos, permit no. 51/MML/08.

Landward of the foredune there is an even sand flat 150-300 m wide, obviously formed by deflation as a result of grazing. There were a lot of livestock in this district at the beginning of the century (Suomenmaa 1925: 223) and the seashore meadows were used for grazing. On the other hand, settlement was very scattered on these poor sandy soils. Also, the forests were extensively felled early this century (Suomenmaa 1925: 225), which increased the aeolian transport of sand. Landwards of the sand flat, now covered by mosses, there are old dune ridges, which wind on account of blowouts. The arcuate blowout dunes in the forest are 2-5 m high and are separated by peat bogs.

Since the shoreline seems to have advanced about 50 m during the past 40 years, one can conclude from this and the height of the base of the old dune bordering on the deflation surface that the age of this dune could be about 200 years. The incipient foredune was probably formed some time in the 1950's. The deflation surface was already as broad as it is to day in the early 1950's. According to Granö and Roto (1989: 52), the duration of shore exposure (the time that the beach has been located between the highest and lowest sea levels) is only 260 years near Vaasa. This is due to the fact that land uplift is rapid and sea level fluctuations are quite small (120 cm).

In summer 1987 the deflation surface was covered by patches of Racomitrium canescens and Empetrum hermaphroditum, with saplings of pine, and by summer 1991 the pines were already 4 m high and the open sand flat had disapperared. The area mentioned above corresponds to the situation in 1987. Recreational use, in the form of camping and motorcycling, has not prevented the invasion by pine forest. On the contrary, it can be clearly seen how the open sand flat of 1950 was covered by mosses and young pines in 1990 (Fig. 21). Counting from the annual shoots, the pines seem to have begun to grow in the early 1970's. Racomitrium is dying under the forest, and recently it has also been covered by sand.  

13. Tisskärssanden, Vexala (10 ha)

The Vexala Peninsula lies north of Monäs, again near Nykarleby (Fig. 3). The whole west coast of this peninsula is characterized by small drift sand beaches, as aeolian material has accumulated between the rocky headlands. The embayment of Tisskärssanden was formed when land uplift destroyed the strait of Tisskärssundet and the island of Frösö became connected to the mainland. The highest points of this isthmus are now about 3 m above sea level. The sands accumulated in the form of a tombolo south of a separate protrusion that is still called Hoppmansholmen on the Basic Map of 1952, although this point was situated about 200 m from the shoreline by 1987. Shoreline displacement during the last 40 years has amounted to an average of 2.5 m a year.

At the embayment of Tisskärssundet three parallel dune ridges have been formed, following the arcuate form of the beach, the youngest developing since the 1970's. Sand has accumulated quite evenly at the base of the lyme-grass, forming a bed about 0.5 m thick. Only the inland edge of this ridge, in front a stand of Salix bushes, is higher (1 m), apparently because the bushes, with birches and alders behind, cause deposition of sand. The damp depression with trees has risen above sea level since the 1940's, when the dune ridge in the middle was still connected to the shoreline and it was growing in size. The oldest dune ridge slopes gently (4o) toward the highest point of the past isthmus (almost 3 m a.s.l.) and its rocky base can be seen on the landward slope. There is only about 0.5 m sand above the cliff. A small rocky island, Tisskär, was apparently once located here. Sand has also accumulated elsewhere on the cliffs, e.g. to form separate hummock dunes on the southern shore of the embayment.

14. Storsand and Lillsand, Pietarsaari (14 ha)

The beach of Storsand is separated by a rocky headland from that of Lillsand lying north of it (Fig. 3). Both these beaches form part of a recreation area belonging to the town of Pietarsaari. Lillsand was harrowed bare in summer 1987. Longshore bars are left drying in front of these beaches at times of low water. In the northern part of Storsand the wind has blown sand onto the cliffs, where it has accumulated around Salix bushes to form hummock dunes. In the middle of the Storsand beach a brook meanders across the sand. The foredune has been replaced by separate dune hummocks 0.5-1.3 m high bound by Leymus arenarius, and further from the shore by Salix bushes, hummocks 0.2-1.5 m high. Juncus balticus is growing abundantly on the sand and binding small sand mounds. Fontell (1926: 187) mentions this species as an important sand binder on these coasts. Sand has also accumulated around trees.

The beaches of Pietarsaari are exposed to NW winds, which are seen in the records of the Mässkär meteorological station, located 7 km north of the beaches, to be the most frequent and most powerful in this area (Climatological Statistics in Finland 1961-1990: 114). The strongest winds usually occur in October, so that the mean wind speed for this month during the period 1961-1990 was 7.2 m/s.

 

Coasts of the Vattaja Cape, Lohtaja (500 ha)

A large part of the Vattaja Cape is in use for military purposes, the broadest open sand fields serving as target practice areas. Wide, continuous open sand fields of this kind would not be possible in the humid climate of Finland without human interference. The area of the open dune landscape was determined from the Basic Map (1987, 1:20 000), and contrasts with the figure of 1400 ha reported by the Lohtaja local council (Suomen matkailuopas 1986: 264), which includes an area covered by forest. The total area of the dune field is even larger than this, however, as it comprises most of the Vattaja Cape, which is part of an NW-SE-oriented esker smoothed by waves. This esker continues as an uninterrupted ridge for almost 30 km under the sea and then bifurcates, having continuations on the mainland of Sweden (Tulkki 1977: 54-57). Land uplift is very rapid in this area, about 8 mm a year (Atlas of Finland 1990: folio 125: 35). When the esker rose above sea level the winds will have blown sand onto the foredunes. The parallel dune ridges as they appear on the Basic Map represent the phases of shoreline displacement. The depressions between the dunes are often damp peat bogs, having formed when the dunes accumulating on the sand spits enclosed the lagoons behind them. This happened to a former pond known as Uusilahti at the beginning of this century (Leiviskä 1905b: map appendix; Mattila 1938: 3). Now this area has been invaded by a peat bog, and partly by forest. The same has happened to many other lagoons on Vattaja Cape that had still clear water at the beginning of this century (Fig. 22). Not only have they been raised by aeolian sand and land uplift but they have also been ditched in many places for drainage purposes.

Fig. 22. The cape of Vattaja (Lohtaja; no. 15-17 in Fig. 3) in 1987. The ponds mapped in 1947 which have now disappeared are shown with broken lines.

Sandy shores continue unbroken for about 10 km on the west coast of Vattaja Cape, where they are exposed to westerly winds. Between the headland of Hakunti and the sand spit of Lahdenkrooppi, the shallows refract the waves in an embayment 3 km wide. Nowadays the beach drift seems to transport sand towards Lahdenkrooppi. The headlands cause wave refraction, and they continue into the sea in the form of shallows. The headland of Hakunti, for example, is connected to a 300 m long shoal with boulders known as Hakunninpauha, and the sandy spit of Lahdenkrooppi also continues out beneath the sea. To the north of this spit the shoreline is quite straight and is oriented in north-south direction for 4 km. There are vast sandy shallows and the surf has moulded giant cusps that continue as submerged transverse bars. South of the tombolo called Kalsonnokka there is an embayment about 2 km wide. Both sand accretion and shoreline advance will proceed most rapidly in arcuate embayments of this kind. The sea is shallow between Kalsonnokka and the island of Ohtakari, which is connected to Vattaja Cape by road. Wave action is weak in this area and the sediments are silty, so that the shore is covered by a reedbed. On the east coast of the cape there are some sandy shores with dunes, where stones and boulders are frequent. Sand has been deposited to the lee of the boulders.  

15. The Karhi dune field

To the north of the Hakunti headland the beach is narrow, only about 100 m wide, but it broadens out near the sand spit of Lahdenkrooppi (Fig. 22; Fig. 3, nr. 15), where sand accretion has been abundant. A forest of pines and alders separates the present-day beach from an old, transgressive dune ridge called Vonganpakka (Fig. 22) that has moved forward onto a peat bog. Mattila (1938: 4, 10) mentions the forest and states that the broadest part of the beach was near Hakunti at that time, while the forest edge came close to the shoreline near Lahdenkrooppi. A beach usually widens when the sand supply is abundant and the shoreline is advancing rapidly. According to Mattila (1938: 10), the oldest trees in the forest were 34-37 years old at that time, so that the Vonganpakka dune must have been cut off by the forest at the turn of the century.

Mattila (1938: 10) and Alestalo (1971: 111, 116) both refer to the dunes between the headland of Hakunti and the sand spit of Lahdenkrooppi as the Karhi dunes. The foredunes here were small in the 1930's, or else there were no dunes at all in places because of grazing by sheep (Mattila 1938: 10-11, 14). Now there is a continuously growing foredune 2-3 m high (Fig. 23) and older parallel dune ridges, partly broken into separate mounds by digging and trampling. Some sand mounds that have not been trampled posses a grey lichen cover.

Fig. 23. A profile across the Karhi dune field (Lohtaja) on 1 July 1987. The location is shown in Figure 22.

Fontell (1926: 184) presents a cross-section through the dune field near Hakunti, showing an alder dune located by the shore (Fig. 24). The sand mounds near the edge of the forest could be remnants of this dune. Now the forest is growing in a damp, shallow depression, as described by Fontell (1926: 185-186) as lying landward of the alder dune and a number of small hummock dunes bound by Salix and Empetrum.

Fig. 24. Profile across the Karhi dune field at the beginning of this century, drawn after Fontell (1926: fig. 2). The transgressive ridge of the Vonganpakka dune can be seen to the right, with uncovered tree stumps on its windward slope. Compare with Figure 23.

Alestalo (1971: 116) has also published a profile across the Karhi dunes, apparently representing the northern part of the shore. This shows a foredune 2 m high followed by a deflation surface (over 30 m wide) and another dune ridge somewhat wider (30 m) and slightly higher. Aeolian processes had been weak on these dunes, concluding from the fact that only 10-20 cm of sand had been deposited around the trees (studied by Alestalo 1971: 117-118) in the course of 25-35 years. The foredune had made no advance. Alestalo (1971: 117) also proposes that the ecological succession must be due to leaching of the dune sand. The deciduous trees growing on the depositional areas (Alnus incana, Sorbus aucuparia and Prunus padus) are replaced by pine, and the grass vegetation gives way to encroaching dwarf shrubs and lichens as the nutrient content of the soil declines and the deposition of sand ceases. The growth of the pines is also detarded, but dendrochronology is not a suitable method for observing the development of the incipient foredune as saplings do not appear on the leeward slopes of dunes until the sand surface begins to stabilize.  

16. The Vattaja dune field

There were no trees on this over 1 km wide dune field at the beginning of this century (Mattila 1938: 4), and the landscape was described as follows (Suomenmaa 1925: 284): 'Stormy days offer a magnificent view, when the foaming water of the crashing breakers approaches from the open sea over the shallow beach and the thick sand clouds rising from the dune crests are blown landwards, burying the dwarf shrubs and the bases of the trees.' Nowadays the dune field is partly covered by forest, but sand is still accumulating around the tree trunks on the slipfaces of the dunes, particularly in the target practice areas. The military use of this area began in the 1950's.

Mattila (1938: 5-12) divided the Vattaja dune field (Fig. 3, nr. 16) into zones parallel to the shore. Thus the open beach is followed by a 100-150 m wide zone of dunes with small, separate lee dunes, embryonal hummock dunes and a gently sloping foredune 1.5-3 m high. The soil surface between the dunes is darkened by coarser material, and there is a deflation surface covered with coarse material landward of these dunes, the lower part of which has an abundant vegetation cover (e.g. Festuca rubra, Leymus arenarius, Juncus balticus, Salix repens, Alnus incana) binding small dune mounds. The humidity of the soil, given the position near sea level, has obviously affected the vegetation. The upper part of the deflation surface was shielded by a stone pavement in places at that time, and was covered by aeolian sand on its landward side, merging into the windward slope of a transgressive dune. Here and there this dune is a vegetationless moving ridge, and elsewhere it is an irregular complex of giant dune hummocks with wind-scoured gaps between them. Laakainperänpakka (Fig. 22) is an ordinary transgressive dune with a gentle windward slope (2-5o) and a steep leeward slope (12-28o against the forest edge and 30-33o in the lower part of the slipface). The relative height of this dune is 7-10 m and it is 200 m wide on average. Kommelipakka (Fig. 22) is a typical dune hummock, the summits of which were covered with alders and varied in height between 17 and 20 m a.s.l., in contrast to the 10-14 m of the sandy gaps between them. The unbroken leeward slope had a gradient of 25-32o on average (Mattila 1938: 5-12).

The Laakainperänpakka dune has been renamed Tarkastajanpakka on the Basic Maps, but the above description still matches the situation quite well. Its sandy leeward slope still seems to be active. The forest cover on the dune has greatly increased compared with the photograph taken by Lemberg (1934: app. 2) in 1926. Fontell (1926: 182) recounts how the dead tops of pines and spruces were protruding from the sand at that time, and explains that the alders, birches and bird-cherry trees that had been growing on the dunes had been replaced by pine. Alestalo (1971: 110-116) traced the advance of the mobile Laakainperänpakka dune by using dendrochronological methods. The dune had advanced 150 m during the period 1750-1970, an average of 0.7 m a year, but had moved only very slowly since 1905, only 0.1 m a year on averege, and did not seem to have advanced at all in the late 1960's (Alestalo 1971: 116). There was still considerable accumulation of sand at the beginning of this century, however, for Mattila (1938: 17) describes how the dune moved with exceptional speed in 1931-32 and totally buried a barn. He reports a rate of advance of 1.0-1.9 m a year, and tells how there was still a 1 m layer of snow on the leeward slope in the middle of June 1932, buried by 0.3-0.5 m of sand (Mattila 1938: 15).

The Kommelipakka dune has remained more stable. It was almost stabilized by the beginning of this century, as sand was being transported only in the wind-scoured gaps (Mattila 1938: 17). There are some high, forested dune hummocks lying proximal to this dune, remnants that show the earlier position of the dune ridge and which now support pines, spruces, bird-cherries, alders, rowans and junipers, partly buried in sand. The surrounding deflation plain was still entirely open at the beginning of this century, but now the lower part of this area is mainly covered by forest and the upper part by an accumulation of aeolian sand. Sand has also covered some young trees and the the stony pavement (Alestalo 1971: 116).

Alestalo (1971: 111) concludes from the land partition map of 1761 that the shoreline has advanced 0.5-1.5 km since then. The breadth of the treeless sandy shore in the 18th century was about 0.7 km. Fontell (1926: 181-182) described the vegetation to the south of the Kalsonnokka tombolo at the beginning of this century as featuring a 100-200 m wide sandy beach covered in places by Leymus arenarius, Honkenya peploides and Festuca rubra. The foredune was formed of ridges 0.5-1.0 m high and 5-10 m long bound by Leymus, and another parallel formation of smaller dune ridges existed landward of this. The ground between the dunes was covered with gravel and small stones. In addition to the plants mentioned above, Juncus balticus and Carex nigra were also present, binding the sand around them. The large transgressive ridges were situated about 0.5 km from the lower limit of the epilittoral zone.

A cross-section of approximately the same area drawn in summer 1987 shows four parallel dune ridges, together with a separate embryonal ridge in places. The average height of the dunes is 1.5 m. Their windward slopes (5-10o, but steepened in places by deflation to 23o) are usually more gentle than the leeward slopes (10-30o). Thick communities of Lathyrus japonicus are growing in the dune slacks. The extreme landward ridge consists only of separate dune mounds, and further inland still the deflation surface is dotted with small hummock dunes bound by Empetrum hermaphroditum (Fig. 25), with Juncus balticus growing between them. Carex nigra has apparently declined in abundance. The surface is broken in places by spherical blowouts about 5 m in diameter, the formation of which is due to the use of this area for military purposes. The edge of the forest is more than 200 m from the shoreline and is marked by birch and alder more commonly than pine. Comparing the records with those of Lemberg (1935: 61-62), the change in vegetation may be seen to have been due to drying of the sandy soil on account of land uplift, as the species that have declined in numbers (Carex nigra, Juncus balticus, Salix repens, Agrostis stolonifera and Calamagrostis sricta) are ones that are characteristic of damp surfaces.

Fig. 25. In July 1987 the deflation surface of the Vattaja dune field (Lohtaja; no. 16 in Fig. 3) was partly covered by a carpet of Racomitrium canescens dotted with small Empetrum hummocks.

17. The bathing beach of Vattaja

The bathing beach of Vattaja lies on the northern sho re of the cape (Fig. 22; Fig. 3, nr. 17), east of the road to Ohtakari, and is sheltered against westerly by this island and the embankment of the road. SW winds predominate in this area, but there are also high winds from the north at times (Climatological Statistics in Finland 1961-90: 114). There were no appreciable dunes in this area at the beginning of this century, and the northern shore of the cape was flat (Mattila 1938: 5), but now the beach is bordered by a 2.5-3.5 m high foredune, the windward slope of which has been steepened by marine erosion (Fig. 26). Leeward of the foredune there are hummock dunes bound by Empetrum hermaphroditum which accumulated about 10 cm of sand in about four years (1987-1991). The soil surface between the hummock dunes is covered by mosses and Placynthiella lichen. The foredune is already marked on the 1955 Basic Map as a set of separate hummocks and its ridge has remained in position since that time.

Fig. 26. A profile across the bathing beach of Vattaja (Lohtaja) on 1 July 1987. The location is shown in Figure 22 (four soil samples).

 

Coasts of the Bothnian Bay

Some shallow depositional bays, indicated on the Basic Map as open sandy shores but now covered with vegetation, are to be found on the coasts of the Bothnian Bay. Their invasion by plants may be due to the cessation of grazing on the shore meadows, although the eutrophication of the coastal waters will also have contributed to this development.

The dune of Mateenpyrstö, situated north of the mouth of the River Siikajoki (Fig. 3), was mentioned by Rosberg (1895a: 94) as a major transgressive dune of the same importance as the dunes of Lohtaja and Tahkokorva, and he noted that it had moved onto arable land. Alestalo (1971: 123-126) also studied it, but it has altered since his time to the extent that it has been separated from the shoreline by a belt of vegetation (Basic Map of 1980, the map of 1970 still shows an open sandy shore). This dune belongs to a sand field formed by wind and wave action shaping the sands of an NW-SE-oriented esker into arcuate, parallel beach ridges, marking the positions of former shorelines. This forested landscape patterned by sandy ridges and intervening peat bogs occupies a total area of about 27 600 ha. 

18. Hietasärkät, Kalajoki (85 ha)

The Hietasärkät dune field in Kalajoki (Fig. 3) is one of the most popular holiday resorts in Finland, featuring a water amusement park, baths, the most intensively used camping site in Finland, two hotels, restaurants, holiday villages and summer cottages. The beach, two and a half kilometres in length and the dry pine forest behind it have been worn through much trampling (Jämbäck 1995: 39). A golf course was opened in the southern part of this area in 1992, and in the north there is a race track. Some sand pits have been deepened to form fishing pools. A surfaced tourist road has been built along the crest of the highest dune.

This dune field is connected with a huge glaciofluvial esker formation (Fig. 3) which continues under the sea (Atlas of Finland 1990: folio 124: 24) and to the First Salpausselkä in SE Finland (Heikkinen & Tikkanen 1987: 243), and the waves have spread the glaciofluvial material into shore deposits several kilometres wide on both sides of the esker core. There are parallel beach ridges covering the sand fields. In low areas the depressions between the sand ridges have been invaded by peat bogs, and it is possible that these low lying surfaces have been moist ever since they were formed (cf. Jämbäck 1995: 24). Wind has deposited sand on the ridges, but the esker core, which consists of coarser material, is represented in the shoreline by a headland known as Tahkokorvannokka (Figs. 27, 28), which has numerous rocks and stony shoals in front of it. The beach is also edged by wide sandy shoals. Westerly winds can blow freely onto the shore, but the archipelago of Rahja and the island of Keskuskari provide shelter against southerly winds. Keskuskari is connected to the main land by a causeway. SW winds dominate in this area, but northerly winds are also frequent in the records of the meteorological station at Ulkokalla on an offshore island (Heikkinen & Tikkanen 1987: 242, 246). The dry, sunny climate (Atlas of Finland 1987: folio 131: 19; Jämbäck 1995 20-21) favours both dune formation and tourism.

Fig. 27. Aerial photograph (no. 92144:6) of the Hietasärkät dune field (Kalajoki; no. 18 in Fig. 3) in May 1992. Sand bars are clearly distinguishable, as is the forested patch of Herrainpaikat. There are many longshore bars in the southern part, while in the north the sand spit of Vihaspauha, formed of parallel beach and dune ridges, stretches out for over a kilometre. Keihäslahti, between Vihaspauha and Tahkokorvannokka, will gradually turn into a lagoon. Compare with Figure 28. By permission of © Maanmittauslaitos, permit no. 51/MML/08.

Fig. 28. Map of the Hietasärkät dune field, Kalajoki (no. 18 in Fig. 3). The hotel at the southern edge is built on the dune of Tuomiopakat, and the transgressive dune ridge to the north of it is called Tahkokorva. The hotel mentioned in text is the northern one.

Waves and winds effectively deposit aeolian sand from both sides onto the road embankment leading to Keskuskari (Fig. 28), while the sandy shore of the camping site immediately north of this is very shallow and over one hundred metres wide. The waves are usually of low energy and are refracted around Keskuskari at times of SW winds. According to Tapaninen (1995: 95) sand has also accumulated northwards beneath the bridge of Keskuskari in a fan-like formation. The beach is bordered here by a 2-3 m high foredune with an escarpment on its windward side which has been moulded by heavy trampling and occasional marine erosion. The leeward side of this dune consists of recent blowover beds. Sand is accumulating on the dune, especially as a result of autumnal storms. The camping site lies in a depression between the foredune and the old dune of Tuomipakat, which is about 20 m high and supports a pine forest. Shoreline displacement in this area has been about 300 m over the last 120 years (Jämbäck 1995: 17). The foredune, which has trapped little pools behind it, continues into the sea as a sand spit known as Riveli (Fig. 28), which dams up a damp meadow behind it as a continuation to the pools.

The beach to the north of Riveli is 20 m wide and ends in a shore bank or abrasion cliff about 2 m high in which the horizontal bedding of earlier shore deposits can be seen. In the north the shore bank is topped by a foredune bound by lyme-grass and slopes more gently because of slumping sand beds. Here summer cottages have been built on and behind the foredune, and hummock dunes have now accumulated around these. Further away from the beach the hummocks are covered by mosses and there are some tree saplings growing in their shelter, the needle litter of which serves to enrich the vegetation cover of the leeward slopes. In the middle part of the beach, near the hotel, it has been necessary to protect the concrete foundations of some cottages with boulders, because the waves are said to have dug sand out from under the cottages during autumn storms.

Alestalo (1971: 118-119), comparing the shoreline on maps from 1868-70 with that existing one hundred years later, found that the shoreline at Tahkokorvannokka (Fig. 28) had moved 80 m seaward as a result of land uplift. Thus shoreline displacement has been about 80 cm a year in the north. One kilometre further south, however, it has moved landward 40 m during the last hundred years in spite of the land uplift, which in this area has amounted to almost one metre in one hundred years. The fine, loose, easily erodible material has been proposed as the reason for this shoreline retreat (Alestalo 1971: 118; Heikkinen & Tikkanen 1987: 246), as such material is susceptible to wave action and the northerly winds in particular can blow onto this part of the beach with their full stregth. The waves tend to mould the beach profile so as to achieve a balance between erosion and accumulation (Uusinoka 1986: 60-61). At the same time the beach profile has naturally become steeper as a result of land uplift, and a steep slope favours both destructive wave action and the movement of sediment away from the shoreline. As a consequence the beach profile again becomes more gentle and accumulation can begin again.

Behind the foredune there is an almost unvegetated deflation surface 100-180 m wide (Fig. 29) which rises very gently in an inland direction (Heikkinen & Tikkanen 1987: 249). The fine material has been blown away from this area and the surface has become enriched with gravel and stones. There are lichens growing on the distal sides of the larger boulders, but the windward sides are barren and polished by blown sand. Trampling has not been so heavy to the north of the hotel, and here the surface is covered by widely spaced Festuca ovina and patches of Racomitrium canescens. There are also low, table-like erosion remnants showing how the deflation surface has been worn down to a lower level. In the south, around the Herrainpakat dune, there are some solitary dune hummocks, the windward slopes of which have been eroded by deflation, leaving sandy tails pointing leeward. The height of these dune hummocks varies between 20-150 cm and the diameter 1.5-10 m. Their sand is markedly finer than that of the surrounding deflation surface.

Fig. 29. A profile across the Hietasärkät dune field (Kalajoki) on 28 June 1987. The location is shown in Figure 28 (four soil samples, plus one further from Tuomipaikat).

The sand at the distal edge of this deflation surface is bound into hummock dunes by Leymus arenarius, with lower hummocks like steps on the slope. These dunes are usually between 0.5 and 2 m in height, and their windward slopes (90o-25o) and the depressions between them have been worn down by deflation. The leeward slopes are gentler (usually 10o-20o), with sand accumulation. At about 8 m above sea level a black charcoal layer can be seen in a soil horizon buried in aeolian sand on the windward slopes of these dunes (Heikkinen & Tikkanen 1987: 263). Nearer the shore the old soil has been worn away by deflation.

Behind the zone of hummock dunes, on the windward slope of a transgressive dune ridge, there is a concave deflation surface, again with an enrichment of coarse grains. There are also many pine stumps with their roots in the old buried soil horizon (Heikkinen & Tikkanen 1987: 249). Deflation has steepened the dune slope, especially between the hotel and Herrainpakat dune (Fig. 28). This deflation slope has a gradient of 10-15o and its upper part ends in a crest with an escarpment (30-35o). The crest is quite broad and runs parallel to the shore, with its highest points rising about 20 m above sea level. The slipface has inclinations of 16-30o. Even young pines are found buried deep in aeolian sand in places on the slipface, while elsewhere the surface is stabilized by mosses. The pines suffer from being buried to a considerable depth, and some of them are dead (Heikkinen & Tikkanen 1987).

The southern part of the dune field features the old forested dunes known as Herrainpakat and Tuomipakat. These are remnants of an older dune ridge, the activation and movement of which, triggered by deforestation and forest fires, has led to the formation of the modern transgressive dune ridge (Heikkinen & Tikkanen 1987). Deflation and erosion by rain and the melting of snow, together with heavy trampling, are gradually eroding the slopes of Herrainpakat (Fig. 30) and uncovering the roots of trees. This dune hillock has clearly shrunk during the last 60 years, and the trees are easily blown down in high winds (Jämbäck 1995: 45).

Fig. 30. Wind and water erosion has uncovered the roots of pines on the trampled windward slopes of the Herrainpakat dune (see Fig. 28). Photographed on 21 July 1991.

According to Heikkinen and Tikkanen (1987: 263), the old surface covered with the soil horizon rose from the sea some 900 years ago and was bound by the vegetation for at least 500 years later, as a clearly discernible illuvial horizon has formed. A dune ridge was formed near the shore during the Little Ice Age, and aeolian processes have become activated again after forest fires, apparently in the 1830's (Heikkinen & Tikkanen 1987: 264; Jämbäck 1995: 13). The map of 1868-70 already shows Herrainpakat as a separate hillock. Heikkinen and Tikkanen (1987: 250) note that the dune has been moving over a level shore deposit in the north, near Tahkokorvannokka, and over beach ridges in the south.

At the beginning of this century this transgressive dune was completely devoid of vegetation and pine stumps had been exposed by deflation on its windward slope. Some of these stumps can still be seen (Fig. 31). According to Rosberg (1895a: 85-86), the slipface moved into the pine forest and the dead trees were felled for fire wood. Sand transport was abundant around 1890, as there were three years in which even stumps 2.5 m high were exposed. Also, the slipface was steep at that time, 30o, whereas now it is usually only 20o or less (Heikkinen & Tikkanen 1987: 257). An aerial photograph from 1947 shows the whole area to be still without any vegetation, and there were no hummock dunes on the windward slope of the transgressive dune, but there were layers of light cover sand in the forest behind the dune. The zone of hummock dunes can already be seen in photographs from 1964, however (Heikkinen & Tikkanen 1987: 258-259). According to Alestalo (1971: 122), sand accumulation had been especially abundant on the slipface in 1929-32, when it amounted to 4 m altogether, and at the same time the dune was increasing in height (Jämbäck 1995: 15). The slipface was moving about 1.5 m a year at the beginning of the century (Alestalo 1971: 123). According to Heikkinen and Tikkanen (1987) the dune has moved almost a metre a year over the last hundred years and has now migrated 200 m inland from its earlier position. Aeolian activity has diminished significantly since the 1940's, when unlimited grazing by sheep came to an end (Heikkinen & Tikkanen 1987: 259, 264). Sand is now accumulating only in some places on the slipfaces as a result of human activities. Some organic layers can be found on the slipfaces, pointing to earlier stable periods (Heikkinen & Tikkanen 1987: 252). Dune migration has now come to a standstill (Heikkinen & Tikkanen 1987: 264), although trampling still prevents the spread of vegetation to the windward slopes.

Fig. 31. There is an arcuate deflation surface on the windward slope of the Tahkokorva dune. Old tree stumps have been revealed as the dune has moved (photographed on 21 July 1991). This area was entirely bare at the beginning of this century (cf. Leiviskä 1905b: app. 8).

From the Hietasärkät area the dune field continues to the southwest in the form of low, forested dune ridges parallel to the shoreline, before rising again at the higher, arcuate ridge of the Viitapakat dune. To the south of Keskuskari the material near the shore is so fine-grained and moist that the vegetation can easily establish itself on the surfaces and there are only small dune formations (Tapaninen 1995: 72). The dunes known as Maristonpakat to the northeast of Hietasärkät have already lost their connection with the present shoreline.

19. Letto, Kalajoki (35 ha)

The peninsula of Letto forms part of the delta at the mouth of the River Kalajoki (Fig. 3, nr. 19; Rosberg 1895b). Its sandy plain features low, parallel sandy ridges deposited by a combination of wind and wave action, alternating with wet or moist depressions. This topography continues to the sea in the form of parallel longshore bars. On Rosberg's map from the end of the 19th century (Fig. 32), the present-day pool of Rantalampi is just closing up at the river mouth and there is not yet any sign of the pool of Letonlahti that is marked on newer maps (Fig. 33). In the middle part of the sandy flat the shoreline has moved over 500 m during one hundred years, and comparison of newer maps shows current shoreline displacement to be about 2.5-5 m a year. Northerly winds can blow freely onto this shore.

Fig. 32. Map of the delta of the River Kalajoki, drawn after Rosberg (1895b: app. 11). The lagoon of Rantalampi is just closing up. Compare with Figures 27 and 33.

Fig. 33. The dune field of Letto (no. 19 in Fig. 3) at the mouth of the River Kalajoki in 1991. The shoreline and ponds of the 1954 mapping are shown with broken lines. The whole area is less than 5 m above sea level.

Agrostis stolonifera binds small hummock and lee dunes on the vast sandy shore plain in the occasionally submerged littoral zone, and these Agrostis dunes had grown 10-30 cm higher by July 1991 and were more frequent than in summer 1987. Most of the sandy plain is devoid of vegetation and bordered by a 0.5-2.5 m high foredune. The grain-size of the material is markedly finer in this area than on the Hietasärkät dune field of Kalajoki. The lyme-grass growing on older dune ridges is sterile, and the ridges have been lowered by deflation and water erosion. The sand is bound by the root systems of the dying lyme-grass. Further from the beach the dune ridges have been levelled to sandy tracts rising less than 0.5 m above their surroundings, the moist depressions between which are covered by a continuous carpet of mosses. The highest dunes in this area lie nearest the shoreline. Trampling is not important behind the foredune, but the sandy shore plain is used for training horses. 

20. Yrjänä, Tauvo

The bay of Yrjänä is situated on the western shore of the Tauvo Peninsula in Siikajoki (Fig. 3), a broad glaciofluvial formation which continues under the sea (Atlas of Finland 1990: folio 124: 24). Both winds and waves have deposited sand onto the beach ridges, which are over one metre high and arcuate, following the form of this pocket beach (Fig. 34). They are separated from each other by wet depressions, and similar depressions further landward have been invaded by peat bogs. The sandy shore is shallow. In the Siikajoki area a new beach ridge is formed at an average interval of 22-23 years (Helle 1965: 31).

Fig. 34. Winds and waves have caused sand accretion on the crest of a beach ridge in the bay of Yrjänä (Siikajoki; no. 20 in Fig. 3). Waves have thrown sand onto and over the ridge (from right to left in the photograph). Ripple marks in the direction of the ridge show the last direction of wind transport. The sand is bound by Leymus arenarius and Agrostis stolonifera as well as Phragmites australis. The parallel beach ridges are separated by wet slacks with willows and alders. Photographed on 27 June 1987.

The grain-size parameters of these ridges are quite similar to those of dunes (cf. Tikkanen 1981: 309; Keränen 1986: 82), and they have very dense vegetation cover, in which Phragmites australis binds the sand effectively. Bare sand can be seen only on the windward slope and crest of the youngest ridge, but even there the leeward slope is covered by Salix bushes and alders. According to Lundberg (1987: 474), Phragmites occurs on dune beaches around brooks, since these sites are moister and richer in nutrients and humus than their surroundings. Plants growing on ridges separated by wet depressions can apparently obtain water more easily than those on real dunes, and in any case habitats that have partly accumulated as a result of wave action contain more nutrients than pure aeolian sand. The vegetation cover on these ridges limits aeolian processes, and aeolian sand is accumulated only in beds that follow the surface and in small mounds on the crests.  

21. Haikaranhietikko, Tauvo ( 30 ha)

The Haikaranhietikko dune field is situated on the Tauvo Peninsula, north of Yrjänä (Fig. 3). At times of low water level wide sandy shoals provide an abundance of sand for aeolian transport. The shore is open to westerly winds. The beach is over 20 m wide and consists of longshore sandy bars with pools between them, sometimes known as ridges and runnels. The nature reserve area of Tiiranhieta occupies in the northern part of this area, and both this and the other beaches of the Tauvo Peninsula are among the best to have been preserved in a natural state of all the beaches in Finland. There are some summer cottages behind the foredune of Haikaranhietikko, but the area has not been heavily trampled nor otherwise altered by man elsewhere than just around the cottages.

The ecological succession that occurs on dune ridges is clearly to be seen here. The incipient foredune is bound by Leymus arenarius, while Hieracium umbellatum and Rumex acetosella are also abundant on the older parallel dune ridge. Both dunes rise 2-3 m above their surroundings. The older dune was still the higher one in summer 1987 (Fig. 35), but the situation had changed by summer 1991, as the incipient foredune had grown 0.5 m in height. There are sand terraces caused by water erosion on the leeward slope of the older dune ridge. On still older dune ridges Leymus arenarius has become sterile and the ridges have been reduced to hummocks less than 0.5 m high and covered mainly by mosses and lichens. Behind this zone of dunes, which reaches about one hundred metres in width, there is a moist depression.


Fig. 35. A profile across the Haikaranhietikko dune field (no. 21 in Fig. 3) on the western coast of the Tauvo Peninsula (Siikajoki) on 26 June 1987 (six soil samples). The locations of the profile and the nature reserve of Tiiranhieta are shown on the map. The whole dune field is less than 5 m above sea level.

Further away from the beach the dune ridges have disintegrated into separate hummocks, the younger of which have lyme-grass growing on them as a relic, while the older ones are bound by Empetrum and lichens (Fig. 36). These dune hummocks, formed as erosion remnants, are quite high, usually 70-150 cm, and have steeper slopes than the more shield-like hummocks that are merely accumulation forms. Rosberg (1895a: 87) reports that at the end of the 19th century the western coast of the Tauvo Peninsula was bordered by low dune ridges 1-2 m high which had earlier been higher. There were birches growing behind the dunes. One 2 m high dune near the ferry house of Haikara had disappeared in the space of ten years. The dune hummocks now lying about 200 m away from the beach must be remnants of the old dune ridges mentioned by Rosberg. On the map drawn by Leiviskä (1905b), the western shore of the Tauvo Peninsula consists of stony headlands with pastures between them. These headlands are now to be seen behind the forested depression, in the form of accumulations of stones and boulders partly covered by aeolian sand. The island of Tauvo had already grown into a peninsula by the turn of the century and was edged with dunes almost throughout (Rosberg 1895a: 86-88).

Fig. 36. Most of the dune hummocks bound by Empetrum in the Haikaranhietikko dune field (Siikajoki; July 1991) are remnants of old Leymus ridges. They have steeper slopes than the hummocks bound originally by Empetrum. Wind direction is from left to right.

22. Ulkonokanhietikko, Tauvo (180 ha)

On the north coast of the Tauvo Peninsula (Fig. 3) there is a vast sandy marsh that is submerged at times of the highest water levels. Lemberg (1935: 67) reports that there was a moist sandy plain 200-1000 m wide here in summer 1926, and landward from it a zone about 500 m wide where Agrostis and Puccinellia were promoting the formation of miniature dunes. Rosberg (1895a: 87-89) mentions that there was a solitary dune mound 3.7 m high in the middle of the vast, bare sandy plain, and the beach was evidently bordered by a 2-4 m high dune ridge at that time (Rosberg 1895a: 87-88; Lemberg 1935: 68). Lemberg reports that this latter dune was located beside a lagoon pond, which has now been invaded by a peat bog vegetation and has even been ditched. The old dune ridge is now 0.5-1.7 km away from the shoreline.

The north coast of the Tauvo Peninsula is open to winds blowing from between north and west. Some low, parallel dune ridges alternating with damp depressions are found in the western part of the area. The highest dunes now rise about 3 m above sea level, and summer cottages have been built in the shelter of them. The western part of the peninsula belongs partly to a nature conservation area and partly to a recreation area owned by the town of Raahe. The area has preserved its characteristics for at least one hundred years. There is still a vast, vegetationless, sandy plain and a marshy meadow that is occasionally flooded. Solitary dune mounds rise from this even basement. They form rows and are elongated parallel to the shoreline. The highest of these are 1.5-2 m high, but most of them are lower and have been reduced by deflation to sandy spots with a growth of lyme-grass. The influence of winds and waves at times of high water levels can be seen in the form of these dune mounds, the windward slopes being steeper than the leeward ones. The Tauvo Peninsula is growing as the parallel longshore bars become joined to the shoreline (Fig. 37), and the peninsula has clearly developed a denser vegetation cover since the aerial photograph of 1975 was taken.

Fig. 37. Aerial photographs of the Ulkonokanhietikko (no. 22 in Fig. 3) in the NE corner of the Tauvo Peninsula (Siikajoki) in July 1975 (top; no. 75223:17) and in early June 1994 (bottom; no. 94113:212). The vegetation has advanced significantly in binding the sand field in the interval between photographs. By permission of © Maanmittauslaitos, permit no. 51/MML/08.

The Tauvo Peninsula lies near the delta of the River Siikajoki, and it is possible that finer material is transported here from the river mouth by beach drift. The material of the northern shores is finer than that of the western shores. 

23. Koppana, Oulunsalo (15 ha)

The Koppana beach is located on the west coast of the peninsula of Oulunsalo (Fig. 3), which represents part of an esker chain surrounded by sand fields that continues in a SE direction to Rokuanvaara and beyond, following the lake basins (Aartolahti 1973: 8). The substantial width of the sand fields is due to the presence of sandstone in the Muhos formation (cf. Alestalo 1986: 150). The Koppana beach lies near the esker core, which consists of coarser material. The highest point, called Salonselkä, is a forested sand field located on the southeastern edge of the area studied here and covered by 3 m high dunes of fine sand. The aeolian material in the Koppana beach is markedly coarser, and the dunes are lower, separate hummocks. There are some summer cottages and a youth hostel on the beach, which has no shelter against westerly winds.

The Koppana beach is marked on the map of Leiviskä (1905b: 52) as a dune field. The area possessed a gravelly headland with a sandy, unvegetated beach 50-75 m wide to the south of it. There were also some small dune hummocks. The open beach is still about 50 m wide, and the shoreline seems to have remained in the same place for several decades (Basic Maps of 1953 and 1988). There are some small stony cusps, in the lee of which finer material has accumulated. The beach is quite steep and the littoral zone narrow.

Wave and wind action has caused a low beach ridge to accumulate on the beach face, with its distal side rising only 20 cm above the sandy deflation surface behind it. There are also older, equally low ridges that have disintegrated into rows of mounds. Empetrum binds the dune hummocks on the deflation surface, which are partly covered by lichens (Fig. 38). The highest hummock dunes are about 1 m high and 6 m in diameter. Deflation caused enrichment of coarse grains on the surrounding surfaces, but Formica cinerea ants bring finer material from the deeper soil layers to the surface and so increase aeolian transport. Hummock dunes are frequent also to be found in the pine forest behind the beach, whereas further away still they are replaced by continuous ridges.

Fig. 38. Shield-like Empetrum dune hummocks rise above the deflation surface of the Koppana dune field (no. 23 in Fig. 3) on the western coast of the Oulunsalo Peninsula in June 1987.

These hummock dunes could be erosion remnants of earlier beach ridges. Obviously more material has accumulated among the Empetrum dwarf shrubs on these remnants as the hummocks have grown in height. This is supported by the fact that they are shield-like in shape, the bedding follows the surface and the proportion of coarse grains is low in spite of the coarse source material (these hummocks contain less than 0.1 % by weight of grains of diameter over 2 mm). The wind has been depositing sand on the hummocks for a long time.

Ice has been repeatedly thrust up onto this beach and has influenced its formation (Alestalo & Häikiö 1975). The slowness of the advance of the pine forest is probably due to these repeated ice-thrust effects. The icefoot transports sand onto the beach. If the beach material is frozen, even a powerful ice-thrust will not have much effect on the shore morphology, as only ice-grooved gravelly surfaces and low terminal push ridges some 20-30 cm in height will be observed the next summer, but if the soil of the beach has thawed before the ice-thrust, larger crescentic mounds and parabolic sand ridges will be formed (Alestalo & Häikiö 1975: 20-23).  

24. Pajuperä, Hailuoto (23 ha)

Hailuoto, the largest island in the Gulf of Bothnia (Fig. 3, nr. 24), is located on the Muhos sediment formation. Its highest parts were deposited by glacial meltwater at the ice margin (Alestalo 1979: 110-111, 1986: 150). The present island of Hailuoto has been formed by four islands merging as a result of land uplift (Alestalo 1979; 1986). Waves, beach drift, ice-thrust in the winter and winds have moulded the sandy soils, although nowadays open blown sand fields are to be found only on the western and north-western coasts. Elsewhere the material is too silty and develops a vegetation cover layer as soon as it reaches above the water level (Alestalo 1979: 117). The sandy beaches of the west and northwest coasts are already marked on the map published by Leiviskä in 1905. The largest active dune field is connected with the beaches that continue from Marjaniemi to Pajuperä (Fig. 39), but these areas are nowadays stabilizing and being invaded by forest. The area of the open sandy dune field and meadow at the accumulation embayment between Pajuperä and Hannuksennokka is now only about 23 ha, and if the areas behind the small forested patches are included, the total area covered by open dune vegetation is about 40 ha, whereas the area of the open sand field on the Basic Map of 1956 was still almost 70 ha. The ecological succession can progress in peace on this shore, although there are some summer cottages and boathouses.

Fig. 39. Location of the dune fields studied in Hailuoto: Pajuperä and the beach to the south of Marjaniemi. On the other coasts of Hailuoto the foredunes are usually lower and in many places vast Phragmites stands prevent aeolian activity.

Alestalo (1979: 117-119), having examined the shore of Pajuperä both in the field and from aerial photographs, divides this sand field about one kilometre wide into the following zones:

The littoral zone extends up to the extreme high water level, about +140 cm. The hydrolittoral zone is a gently sloping shore platform 300-500 m wide with ice-push boulders and megaripples.

The geolittoral zone includes a 5-10 m wide lower beach with bare sand and ripple marks, and also a foredune comprising the upper beach, dune ridges and further leeward dune mounds. A deflation surface belongs to this zone, too. Beach cusps, storm ridges, ice-push features and embryonal dunes occur on the upper beach. There are two or three parallel foredune ridges, 2-3 m high, bound by fertile lyme-grass and broken in places by wind-scoured gaps. The leeward dune mounds are separated by a network of deflation surfaces. The flat deflation surface behind them is 100-150 m broad and 110-140 cm above sea level, and is enriched with coarse sand at the surface and with silt in the depressions.

The epilittoral zone contains both young and old hummock dunes. The young ones are round, 20-30 cm high and 1-1.5 m in diameter. The pines of the surrounding deflation surface were under 20 years old in 1979, but those around the old hummock dunes are now at least 60 years old. The cover sand beds are even older than the hummock dunes and are covered by pines and dwarf shrubs. There are also dead deflation surfaces with a cover of coarse sand and old littoral boulder pavement strips. About 800 m away from the present shoreline there is a parabolic dune formed by winds blowing from the SW or WSW, and there is an active blowout on the windward slope. Alestalo (1979: 119) concludes from the growth rate of buried and later exposed trees that the dune ridge has shifted 200 m in 120 years. On the windward slope there are dune hummocks 2-3 m high bound by Juniperus communis. The crest of the parabolic dune, broken by wind-scoured gaps, rises 12 m above sea level. The active slipface, with gradients up to 30-35o, has buried pines and advanced over mire vegetation.

These zones described by Alestalo (1979: 117-119) can still be seen, as the shore has not changed greatly during the past fifteen years. There are terraces formed by water erosion on the leeward slopes of the foredune (Fig. 40), and some of the older dune ridges have disintegrated into a field of sand mounds. The flat deflation surface features small hummock dunes 10-20 cm high and bound by Empetrum. In places the groundwater level is near the surface and Drosera rotundifolia is growing in the moist sand. Yearly fluctuations in sea level are significant, but because of land uplift the shore platform of the hydrolittoral, as described by Alestalo, is more frequently left exposed in spite of the fact that the eustatic rise in sea level has slowed down the rate of shoreline displacement from 9 mm a year (Alestalo 1979: 109) to under 8 mm.

Fig. 40. Sand terraces formed by water erosion on the leeward slope of the foredune in the dune field of Pajuperä (Hailuoto; no. 24 in Fig. 3) on 23 June 1987.

Comparing Basic Maps of different ages (1956 and 1980), the shoreline seems to have progressed over 150 m in 25 years in the southern part of the Pajuperä embayment, which is about 6 m a year. In the northern part of the embayment, near Hannuksennokka, the shoreline seems to have remained unchanged during this interval. The beach profile is steeper near Hannuksennokka than in the south, and the material is coarser. Longshore bars are also more abundant on the southern part of the shore, showing material transport southward from Hannuksennokka. According to Alestalo (1979: 117) material may have been transported here by beach drift even from the eroding shore of Marjaniemi. The other sand sources, mentioned by him, are frozen sand slabs on the underside of grounded ice and a high air pressure with north-westerly winds, which can cause the sea level to fall by more than a metre, exposing the sand of the hydrolittoral platform for wind transport. 

25. Marjaniemi, Hailuoto (27 ha)

To the south of the stony, boulder-rich headland of Marjaniemi (Fig. 3, nr. 25) there is a sandy beach more than one kilometre long bordered by parallel dune ridges. A holiday village with restaurant, a lighthouse and a fishing harbour attract tourists to the area, and thus the shore is much more seriously trampled than that of Pajuperä. Nowadays the area of the open, unbuilt dune landscape is about 27 ha, whereas it covered over 50 ha on the map from 1956.

The same kind of zonation is to be found on this shore as at Pajuperä. In the hydrolittoral zone, parallel longshore bars built by beach drift and waves cover the surface of a wide shore platform that remains partly subaerial at times (cf: Keränen 1986: 80). There were also berms 10-20 cm high in summer 1987, showing the phases of lowering of the water level. Some embryonal dunes are developing on the gently sloping windward side of the incipient foredune, which reaches 2.5-3 m above sea level and 1.5-2 m above its surroundings and has two older, parallel dune ridges behind it. In the lee of the wind-scoured gaps sand has fanned out to form 'deltas'. Water erosion has formed terraces on the leeward dune slopes, and behind these dunes is a levelled deflation surface with hummock dunes.

When Lemberg (1934: 73-75) studied this area at the beginning of this century there was a sand field 300 m wide bordered at its landward edge by a small, forested dune. The flora of this shore has not changed much over the decades, but the frequencies of the species and the topography differ from the earlier situation. Earlier there was a sand flat characterized by miniature Agrostis dunes and the area was used for grazing (Leiviskä 1905b: 65). According to Alestalo (1986: 153), the formation of deflation surfaces and transgressive dunes is connected with the grazing of sheep, which destroyed the lyme-grass. Grazing on the coastal dune meadows came to an end in the 1950's (Alestalo 1979: 119). After this the sandy surfaces rapidly gained a forest cover and dune ridges have again been formed on this shore with the same rhythm as in the inner parts and on the north coast of Hailuoto. The the interval of 22-23 years in the formation of dune ridges may be connected with fluctuations in the level of the Baltic Sea and the incidence of storms (Alestalo 1979: 116-117).

The waves erode the stony promontory of Marjaniemi, and beach drift carries material southward. This is shown by the grain-size of the shore material, which becomes finer southward, and by the beach profile, which becomes gentler, together with the longshore bars and the rate of shoreline displacement. Anyway, the shoreline has advanced at most only 40 metres seaward in the course of 25 years in the southern part of this embayment.  

26. Virpiniemi, Haukipudas

This area was included in the present data only in order to compare the grain-size parameters of dunes of different ages. Aeolian transport is no longer significant on the shores of Virpiniemi (Fig. 3), but some small hummock dunes are still being formed around dwarf shrubs. The dry Calluna-Cladina pine forest contains a parabolic dune formed by SW winds, with its crest rising over 15 m above its surroundings. The base of this dune lies 15-16 m above the present sea level, so that this area must have risen from the sea around 200-300 A.D. (Koutaniemi 1986). Proximally to the dune there are parallel forested beach ridges of a regular height and width, following the contours. Nowadays aeolian processes are in evidence only on the west coast of Virpiniemi, on the trampled beach of a holiday village. Landward of this beach is a partly forested dune ridge 2 m high, the base of which is less than 5 m above sea level, so that it must be only about 500 years old. It was probably formed during the Little Ice Age.  

27. Röyttänhieta, Simo

This shore and that of Tiironhiekka (Fig. 3, nr. 27) are among the dune fields studied by Lemberg (1935: 68-71). These shores are good examples of sites where aeolian activity has stopped during this century.

Röyttänhieta is situated on the east coast of the peninsula of Karsikko and is separated from the present shoreline by high pine forest. The vegetation cover of this dune field is still poorer and more widely spaced than that of the surrounding areas. The sandy shore of this area was covered with Honkenya peploides at the beginning of the century.  

28. Tiironhiekka, Simo

Tiironhiekka is located on the east coast of the peninsula of Ykskuusi (Fig. 3, nr. 28). The sandy shore is covered by thick grass or forest in places, while elsewhere storm waves have eroded sand away from this low-lying shore. At the beginning of this century there was a 10 m zone characterized by Honkenya and landward from this a 60 m zone of low dunes and lyme-grass. There was also a 230 m wide lichen-rich heath zone with Racomitrium canescens (Lemberg 1935: 70). Now there is no dune vegetation left and all the shore formations are the result of wave action. 


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