Wentworth scale of Grain size for Sediments

Table 4

Boulder

above 256 millimeters, The most coarse grained, has high environmental energy meaning strong wave action: larger particles which are closer to the shore, and is found in stream beds near the source areas of rivers

Cobble

64-256 mm, grain size is coarse, in the gravel category, High environmental energy meaning strong wave action: larger particles which are closer to the shore

Pebble

In the category of gravel, less coarser than cobble, and size ranges from 4-64mm, moderate environmental energy meaning particle size.

Granule

2-4 mm, In the category of gravel, grain size is slightly coarse (meaning thick), moderate environmental energy meaning particle size

Sand

Size range is 1/16mm - 2mm, grain size is slightly fine, mid to low environmental, Ex: Beach sand,

Silt

1/256mm to 1/16mm, NOT gravel, finer grained, feels gritty in teeth, low energy of the depositional environment

Clay

1/4096mm to 1/256mm, fine grained, NOT gravel, Microscopic; feels sticky, Low energy of the depositional environment