Clastic Sedimentology And Petrography-quiz & Test II

One of lake lakes a body of water of 2 hectares (5acres) or more in area; however, others have defined lakes as waterbodies of 5hectares hectares (12 acres) acres) and above, or 8 hectares (20 acres) and above.

Lakes in regions with large changes between summer and winter can have annual laminations (varves) of clay rich in organics during the summer (anoxia) and of silt in winter (during storms).

Aeolian sedimentary processes are those involving transport and deposition of material by the wind.

Winds of 100 ms-1 or more are recorded during hurricanes, but strong winds over land areas are typically around 50 ms-1, and at these velocities the upper limit on the size of quartz grains moved by the wind is around a half a millimetre in diameter, that is, medium sand size storms.

At high wind velocities silt- and clay-sized particles are carried as bed load.

They are arid areas that receive less than 500mm yr-1 precipitation

An erg is an area where sand has accumulated as a result of aeolian processes.

Grain roundness is therefore a characteristic that can easily be seen in hand specimen using a hand lens, or will be evident under the microscope if a thin-section is cut of an aeolian sandstone

Most modern and ancient wind-deposited sands are quartz arenites.

Aeolian carbonate deposits are less stable features than dunes made of quartz sand.

If the wind direction is onshore, wind-blown carbonate sands can accumulate and build up dune bedforms.

Aeolian ripples have extremely variable wavelengths (crest to crest distance) ranging from a few centimeters to several meters.

Barchan dunes form where there is an abundant supply of sand.

Draas are usually made up of dunes on the stoss and lee sides, but a single slip face may develop on some lee slopes.

A lagoon is the marine-influenced portion of a drowned valley.

Sediment supply to the estuary is from river sources only and the processes that transport and deposit this sediment are a combination of river and wave and/or tidal processes.

Difference between estuary and delta is that a delta retrograde inwards into the lake or sea. A estuary all the sedimentation occurs in the drowned valley

An estuary developed in an area with a Llargetidal range and weak wave energy will typically have three divisions. 

Bay  head delta: Is the zone where fluvial processes are dominant

An estuary is a body of salt water separated from the deeper sea by a shallow or exposed barrier beach, sandbank, coral reef, or similar feature. 

Delta form and facies are influenced by the size and discharge of the rivers, the energy associated with waves, tidal currents and longshore drift, the grain size of the sediment supplied and the depth of the water.

In the transfer zone the streams are actively down cutting, removing bedrock from the valley floor and from the valley sides via downslope movement of material into the stream bed.

The overbank area or floodplain is the area of land between or beyond the channels that (apart from rain) receives water only when the river is in flood.

The line of the deepest part of the channel is called the thalweg.

A braided river contains mid-channel bars that are covered at bank-full flow.