Fossil soils from abrasive southern Baltic coastal sections and problems with their classification: A case study from Ustka Bay, Poland

Abstract

This study aimed to identify the main depositional and soil-forming phases in the middle section of the Polish Baltic coast and determine the history of its landscape development. An attempt was also made to define new qualifiers to describe these compacted and eroded soils (including fossil soils), which have not previously been included in the WRB classification. The study was conducted in cliff sections located in the southern Baltic coastal zone. Selected physical and chemical properties were determined from four soil profiles using standard methods. Additionally, peat, peat-like material, mursh, and charcoals were dated using the radiocarbon method. Environmental reconstructions based on fossil soils have provided information about the development of the coast in the context of periods of relative climate stability that allowed the formation of soils of various types. The presence of sediments of different origin (glacial till, fluvioglacial and aeolian sands, interbeddings of peat, mursh and peat-like material) in the profiles compared with the obtained radiocarbon dates allowed for an assessment of the impact of environmental conditions on the potential for soil formation over thousands of years. The oldest soils, represented by Akrofluvic Stagnic Gleysols and Fluvic Stagnic Gleysols, were dated back to the Preboreal/Boreal period,whereas the youngest fossil soils (Albic Podzols (Arenic) and Aeolic Dystric Arenosols)) were developed in the SA2 phase of the Subatlantic period. The contemporary soil cover was represented by poorly developed Aeolic Dystric Arenosols with initial features of the podzolization process. No soils dated to the Atlantic period were found. Our findings are complementary to those of other studies on the history of the Polish Baltic coast and can be used for comparing with the soil cover development in other coastal regions of the Baltic Sea.