The typical landscape of this coastal area is formed by a broad Litorina Sea terrace with relict lagoonal lakes (Sloka, Kanieris, Engure etc). The narrow (0.5-1.5 km) present-day coastal zone with low dune ridges and series of beach bars separates the bogged-up flat Litorina terrace plain from the Gulf of Riga. Recorded in the geological structure are two local Litorina Sea regression-transgression events from this time. In the course of marine regression, long spits were formed, consisting of gravel and sand. These spits, the Litorina seabed, are naturally saturated with pieces of amber. These are the so-called ‘amber zones’, i. e. exposed Litorina Sea lagoon strata with amber and rich deposits of marine mollusc shells.
This was evidently a factor promoting settlement in the region in the Stone Age. Five Stone Age settlement sites have been found in this coastal zone, from the River Lielupe estuary at the southern end of the gulf up to Cape Kolka in the north: Varnaskrogs, Romi-Kalnini, Silinupe, Gipka and Purciems. Some other single find places along this western coast of the gulf are known – at Dubulti, between Asari and Sloka and other locations. We are aware that there are still a large number of Stone Age sites awaiting discovery by archaeologists along this ‘gold coast’ of the Gulf of Riga.
One of the more important excavated sites is Silinupe, established on the coast of an ancient lagoon by seal-hunters, fishers and amber collectors.
The Silinupe settlement site is located along a depression between a beach-bar and dune ridges in a small natural hollow, protected from the sea winds. Geological and palynological data suggest that settlement here dates from the Subboreal, during the regression of the Litorina Sea second stage. Later, the site became bogg-ed-up, and so at the settlement site Stone Age dwellings, hearths, abandoned fishing and hunting equipment, pottery vessels and amber jewelry were covered in peat and well preserved. The site was discovered in 1953 and excavated in 1954 and in 1988 and 1989. The archaeological material showed that the site was occupied in the Middle and Late Neolithic, i. e. mainly in the 3rd millennium BC.