Focus on Sedimentary Environments

A large saline lake

The Great Salt Lake, Utah, USA


	Beach sediment from southern Great Salt Lake. Scale in mm.

Sediment texture

Look closely at the large image of the sediment. You should be able to distinguish two types of sand, each with a distinct size and grain shape. Describe the grain size and grain shape of each, then check your answers below. Further information on these and other sediment properties.

The finer size fraction

Identify the predominant grain size(s) in the finer sand size of the sample: granules very coarse sand coarse sand medium sand fine sand very fine sand silt and clay	Now identify the dominant grain shape(s) in the smaller size fraction: equant (cubic or spherical) oblate (disc-shaped) bladed prolate (rod or roller shaped)
How would you describe the rounding of this sample (more than one answer may be correct)? very angular angular subangular subrounded rounded well rounded	We shall look more closely at the nature and origin of these grains in later images.

The coarser size fraction

Identify the predominant grain size(s) in the coarser size fraction:

Now identify the dominant grain shape(s) in the coarser size fraction:

What are these coarser grains likely to be?