The composition of the Quaternary surface sediments in the Coastal Area is known in detail since the making of the geological map and especially since the systematic soil survey. The knowledge of the deeper Quaternary sediments however remains still fragmentary .Field work by the Center for Hydrogeological Research at the State University of Ghent has provided new data about the relief of the Tertiary substratum and the lithostratigraphy of the Pleistocene and Holocene sediments of the eastern part of the Coastal Area. A south-north section indicates the existence, in the burried surface of the Tertiary substratum, of two degradation levels (between -17 and -22 and between -8 and -6). Several lithostratigraphic units have been distinguished. The deepest deposit is the gravel-sand Ostend formation of Eemian age. This deposit is covered by the sandy Uitkerke formation of Weichselian age. The Wenduine formation on top of this sand is very heterogeneous; it has been formed during the transition between Pleistocene and Holocene. Along the edge of Inner Flanders the -8 level is overlain by the clayey Meetkerke formation with Hydrobia. In seaward direction this formation becomes sandy when passing laterally into the Houtave formation. The chronostratigraphic relationship between the two formations is not clear although the latter was probably deposited during the Atlantic. They are covered by the sands of the Zuienkerke formation, of which the northern part is also of Atlantic age. During this period and the Subboreal the Nieuwmunster peat was formed. This peat has been covered by the Dunkirk formation, except in the "Moere" of Meetkerke.