AbstractThe presence of glacial marine drift, a hybrid deposit containing sub-fossil shells of age about 12,000 years B.P. in the lowland of Western Iceland, together with a system of presumed lateral melt-water channels with associated deposits, over and around the rim of the bounding ridge and valley terrain, suggests that piedmont ice in the lowland, resulting from coalescence of ice streams from the higher ground inland, floated as an ice shelf as the ice thinned and sea-level rose. The deposits in the area may be the result of fluvial transport in englacial and subglacial conduits, with subsequent deposition on dry land or in water of varying depths. Till is found in varying, but ususally small, proportions in the glacial marine drift but is otherwise absent except in the extreme north-east of the area.