Deltas form wherever rivers encounter standing bodies of water such
as lakes or oceans. The sudden decrease in energy causes the river to drop
its sediment load. Deltaic deposits therefore become finer grained the
farther out into the lake or ocean (distal edge). Across the delta, they
are coarsest in the distributary channels and finest away from the channels.
Many deltaic deposits resemble lake or shallow
marine deposits at their distal margins and river
deposits
at their proximal margins.
Delta building into lake. SE Alaska. |
Delta and alpine lake. Banff National Park, Alberta |
Delta and alpine lake. Grand Teton National Park, Wyoming |
Sediment deposited from Puyallup River, Commencement Bay, Tacoma, WA. |
Distributaries near mouth of Mississippi Delta, Louisiana |
Back to depositional environments.
Back to sedimentary rocks--features.