A foreset bed is one of the main parts of a river delta.
As the sediments are deposited on a sloping surface the resulting bedding is not horizontal, but dips in the direction of current flow toward deeper water.
A cross-section of a delta shows the cross bedding in the direction of stream flow into the still water.
The foreset bed is formed when a stream carrying sediment meets still water.
The deposited sediment builds up over time, and a delta is formed.