Focus on Sedimentary Environments

A tropical carbonate beach

Bolongo Beach, St Thomas, US Virgin Islands

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beach sediment
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enlarged image
Carbonate gravel on Bolongo Beach
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Describing the sediment

Describe the beach sediment seen in the image above, using a standard description scheme. Make sure that you include in your description: grain size, sorting, and grain shape. Further information on these and other sediment properties.

Once you have written your description, check it by answering the questions below:

Identify the predominant grain size(s) in the lower part of the photograph (there may be more than one correct answer):
boulders
cobbles
pebbles
granules
very coarse sand
coarse sand
medium sand
fine sand
very fine sand
silt and clay
Describe the sorting seen in the sample:

very well sorted
well sorted
moderately well sorted
moderately sorted
poorly sorted
very poorly sorted
Identify the dominant grain shape(s):

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

 


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