depositional environments ESC 240

terrestrial environments (6)

• glacial

• desert

• lake

• alluvial fan

• braided stream

• meandering stream

glacial feature and interpretations

• unsorted unstratifes till, striations

• cold climatse, moving ice

desert features aadn interpretaions

• well sorted, cross bedded sandstone, evaporites, little organic matter

• arid climate, eolian transport, interior drainage

alluvial fan

• poorly sorted, cone shaped sedimetn body @ base of mountain

• high energy, short distance transport from steep slopes. change in gradient causes rapid depositions

braided stream

• course sand and gravel, multiple channels, cross bedding

• high sediment load, highly variable water flow

meandering stream

• fine sand and mud, point bar (inner), cut bank (outer), natural levees, floodplain

• lower gradient, cositent water flow, abundant suspended sediment, well developed land with vegetation

lakes

• fine grained lalyered muds and silts, freshwater fossiles

• low energy, courser sed near edge, fine in center, local precipitation

marine environment

• carbonate reef

• continental shelf

• abyssal plain

carbonate reef

• massive limestone composed of cora l and fossiles with zones: reef front, reef flat, lagoon

• warm shallow clear tropical water, reef builders

continental shelf

• well sorted sand and stilt with borrows and marine fossils

• shallow well oxygenated water influenced by waves and currents

abyssal plain

• very fine clay and silt on continental crust

• deep low energy

marginal marine envrionment

deltas

deltas

• a coursening upward sequence: Pro-delta (clay) →delta front (silt) →delta plain (sand)

• river mouth environments where sediemtns is built into a standing body of water. progrades upward. similaar to turbidite deposit