Structure and micromorphology of glacial and non-glacial deposits in coastal bluffs at Sensala, Western Latvia

The article reports results of structural and micromorphological investigation of heavily contorted sequence of glacial and non-glacial deposits. The main part of Pleistocene sequence compromises two units of different till facies, glaciofluvial, glaciocustrine and marine deposits. The top of section was truncated by the glacial Baltic Ice Lake waters. This abrasion surface is marked by an occasional concentration of erratic boulders or boulder pavement, and covered by a thin layer of nearshore sediments, in places - by postglacial dune sand. The structure of Pleistocene deposits suggests multiphase glaciotectonic deformation including initial pro-glacial folding and faulting, following sub-glacial reshaping of preceding glaciotectonic structures and, finally, deposition of the upper till unit, and dêcollement. The OSL dating from the marine fine grained sand revealed that it was last bleached 43-45 thousand years ago, yielding to the Middle Weichselian age of the outcropped Pleistocene sequence.