What Are Lake Deposits?

Definition

• A lake deposit is a layer of sediment on the bottom of a lake. Lakes do not have a strong water flow to carry sediment particles away like rivers, streams and oceans do. The fine-grain particles can build up for hundreds of years without being washed away.

Sources

• Sediment can be deposited on the lake floor by way of two sources. Internal deposits, also known as autocthanous sediments, can include the remains of aquatic life, plants, plankton and other chemicals or minerals present in the immediate area. External deposits, or allochthonous sediments, can be any number of materials brought in from a stream or river feeding the lake.

Deposit Arrangement

• Streams and rivers feeding a lake will deposit larger particles near the entry point. Smaller particles from these sources will be deposited farther out into the lake. Essentially, particles fan out over a distance, from larger-grade to finer particles. The deposits occurring from internal lake sources will be evenly distributed throughout the lake bed.

Uses

• Lake deposits are examined for several reasons. Since lake deposits can go undisturbed for several years, it can indicate previous life forms, climatic conditions and ecological influences. By studying these deposits, you can get a glimpse at the lake conditions, aquatic occupants, weather and other factors that were present hundreds of years ago. You may even find life forms now extinct and be able to study other sediment deposits nearby it to establish whether extinction was caused by contributing factors.