Lammin lössi

The aeolian silty deposits found in Lammi region are commonly known as Lammi Loess. The term is established even though there are no extensive research done with modern sedimentological methods and some of the previous research on the topic are questioning the completely aeolian nature of these deposits. The purpose of this research was to determine how silty deposits known as Lammi loess fit into the definitions of loess, what type of surface textures can be detected from the deposits grains and in what extent and manner Lammi loess occurs in the Lammi region. The loess deposits of Lammi were studied using field observations and grain size analyses. The sediments grain surface textures were analyzed using scanning electron microscope (SEM). The aim of this study was to achieve an extensive understanding of the deposits properties and occurrences in the Lammi region, and also of the typical surface textures of the grains. 18 sediment samples from ten different locations in Lammi was used as material for the study. In addition one dune sample was used as a point of comparison. The locations were situated at 117-166 m asl. (meters above sea level) and majority of them were located mainly below the highest shore of the Baltic Ice Lake (162 m asl.). Lammi loess is moderately sorted aeolian deposit, consisting mainly of coarse silt and fine sand. The deposits were formed when sediments uncovered by the drop of waterlevel in the Baltic basin were exposed to aeolian activity. The source material of these deposits are local and deposition occurred rather quickly. Lammi loess occurs as rather small and local deposits on the slopes of deltas and hills. The formations are more focused on the north-west slopes. Lammi loess has several characteristics typical for loass, but as a whole it is very individualistic formation with properties that are between loess and coversands. The Lammi loess deposits resemble loess in regards of their texture, color, porosity and skewness, but the distribution of sand sized grains matches that of coversands. Some of the studied sediments were either completely or partially deposited in water.