Gilbert-type delta A river delta which consists of a wedge-shaped body of sediment, comprising relatively thin, flat-lying, topset sediments, long, steeply dipping foresets which prograde (see progradation) from the river mouth, and thinner, flat-lying, bottomset or toeset deposits. Gilbert-type deltas are often developed in lakes, where river water and lake water are of the same density. It was first described by the American geologist Grove Karl Gilbert (1843–1918).

Gilbert-type delta A type of river delta which consists of a wedge-shaped body of sediment, comprising relatively thin, flatlying, topset sediments, long, steeply dipping foresets which prograde (see PROGRADATION) from the river mouth, and thinner, flat-lying, bottomset or toeset deposits. Gilbert-type deltas are often developed in lakes, where river water and lake waters are of the same density.