The faunal composition of Upper Pleistocene-Holocene sedimentary sections was investigated from several boreholes in the coastal areas of the northern and eastern Marmara Sea. The boreholes penetrated to pre-Quaternary basement and contain sediments deposited in near-shore environments, such as lagoons, estuaries and deltas. During the post-glacial transgression, rapidly rising sea level drowned these littoral areas, progressively transforming into their present form over the last 9.5-10 ka BP (uncalib.). Thus the lower Kucukcekmece valley became a lagoon, while the Golden Horn became an estuary. On the northeast coast, the Kurbagali delta was submerged. When the rate of sea level rise decreased at about 5000-6000 years ago, the influence of Mediterranean water on the faunal assemblage was surpassed by salinity tolerant forms, probably due to increased freshwater and sediment input on land. (c) 2007 Elsevier Ltd and INQUA. All rights reserved.