Longshore movement of beach materials builds bars across inlets and recurved spits off points. At Eagle Lake, a canal built around 1920 has been completely closed off by beach sand. Similar sand spits can be found 50 feet above current lake level marking the Pleistocene level. If the stream input is relatively large, the deposits build out into the lake as a delta . If input is smaller, they may be completely dispersed by longshore drift.
Wind also carries materials into lakes.
In some environments massive amounts of sand may be transported, but in all environments dust, pollen, leaves and other light debris will end up in the lake. Materials from outside the basin are called allochthonous. Remains of plants and animals dying in the lake often fail to completely decompose. Clam and snail shells, diatom frustules, and peat from marshy littoral areas all contribute to the basin filling. Any lake with an outlet may be thought of as being kept in its basin by a dam.