The Fossvogur layers are among the best known sedimentary formations in Iceland. The sequence is made of marine sediment with subfossil shells, fluvial beds, and till layers both below and on top of the marine part. All the sequence is resting on the striated Reykjavík olivine tholeiite basalt.
The layers can be observed in Fossvogur, in Nauthólsvík and in Skerjafjörður. They also have been found in grounds in Reykjavík west, such as in the Iceland University campus.
The Fossvogur layers have been known among natural scientists from the 19th century and have been investigated and discussed in detail. Many types of molluscs are found, bivalves, cochleae and barnacles. All of them are still living around Iceland today.
The Fossvogur layers are from the late glacial times. Radiometric age determinations on the shells give 12,500-13,000 years BP, or from the Alleröd stage, and the upper till is therefore of Younger Dryas age.
The Fossvogur layers can best be investigated at the head of the Fossvogur inlet and along the northern shore where they form low cliffs. The fossile shells, variable sedimentary layers and underlying basalt can easily be found.
Árni Hjartarson, 2010.