Paleoecological use of land snail shells is no longer a new field of science. They are studied by malacologists and palaeontologists who specialise in the study of molluscs.
During the last glaciation, loess, a light yellow, fine-grained sediment, was deposited over large areas, mainly in the periglacial regions of Eurasia and North America. In addition to its many advantages, it has also provided excellent preservation of land snail shells, which can be studied in spatiotemporal resolution.
The extraction of snail shells from loess is a multi-step process using tap water and solvents to obtain the shells suitable for identification. One of the disadvantages of loess snails is their size, which ranges from 1mm to 3 cm, but most of them are less than 1 cm. Species identification of snail shells is a complex process that considers the morphological characters on the shells and verifies them using identification books and reference materials.
The paleoecological interpretation is based on the fact that the snails found in loess, which are only a few tens of thousands or even hundreds of thousands of years old, still have descendants living today, which can be studied in their own habitat. Assuming that the ‘older relatives’ had similar habitat requirements and taking into account the percentage distribution of the different species per sample, we can generate an environmental and climate reconstruction.
Environmental parameters studied for the snails include temperature, vegetation cover and humidity requirements. If a sample contains a high proportion of warm-loving species that prefer open vegetation, it can be inferred that the environment at the time of deposition of the loess layer containing the sample was an open grassland (steppe) with a comfortable temperature. Following this analogy, a high proportion of species preferring closed vegetation would suggest extensive woodlands, while a high proportion of cold-preferring species would suggest a cold steppe, possibly tundra environment.
Using this methodology on a loess-paleosol section sampled at high resolution (e.g., 4 cm sediment horizons), combined with absolute age data (typically radiocarbon or optical dating), the results can be correlated with global climate curves. By examining samples with the appropriate resolution, we have achieved climate and environment reconstructions with a resolution of a few decades for several loess-paleosol sections along the southern border of Hungary.
This blog was edited by the editorial board.