Sedimentary rock in which at least 50 percent of the constituent particles were derived
from erosion, weathering, or mass-wasting of pre-existing earth materials, and transported
to the place of deposition by mechanical agents such as water, wind, ice and gravity.
The conglomerate, sandstone, mudstone, and wackestone categories are not defined as
kinds of clastic sedimentary rocks because rocks meeting their purely grainsize based
definitions might also be iron-rich, phosphatic, or carbonate. This is based on GeoSciML
allowance to assign rocks to more than one lithology category. For example to categorize
a rock as a clastic conglomerate requires assignment ot the 'clastic sedimentary rock'
category and to the 'conglomerate' category. Particularly for fine-grained sedimentary
rocks, distinction of 'intrabasinal' versus 'clastic' genesis can be very interpretive.
In practice the use of clastic mudstone terminology as opposed to carbonate mudstone
terminology may be dermined by a priori knowledge about the rock being categorized.
If it is associated with other clastic rocks, the clastic categories will be favored,
if with cabonate rocks, the carbonate categories will be favored.
