Here's a breakdown:
* Detrital sedimentary rocks are formed from fragments (detritus) of pre-existing rocks.
* The size of the fragments is the most important factor in determining the rock type.
* Grain size is classified using the Wentworth scale, which categorizes rocks based on their particle size:
* Conglomerates and breccias are made of gravel-sized fragments (larger than 2 mm). Conglomerates have rounded fragments, while breccias have angular fragments.
* Sandstone is composed of sand-sized particles (between 2 mm and 1/16 mm).
* Siltstone is made of silt-sized particles (between 1/16 mm and 1/256 mm).
* Mudstone and claystone are composed of clay-sized particles (smaller than 1/256 mm).
While grain size is the primary factor, other criteria can also be used to further classify detrital sedimentary rocks, including:
* Mineral composition: What types of minerals make up the rock?
* Cement: What type of material binds the grains together?
* Sorting: How well-sorted are the grains?
* Rounding: How rounded or angular are the grains?
However, grain size is the most fundamental and widely used classification scheme for detrital sedimentary rocks.
