Here's a breakdown:
* Conglomerate: Made up of large rounded fragments (greater than 2 mm in diameter), often with sand and smaller grains filling the spaces between them. They are often referred to as "gravel" or "pebbles".
* Sandstone: Composed of sand-sized grains (between 0.0625 mm and 2 mm in diameter). These grains can be made up of various minerals, like quartz, feldspar, or rock fragments.
* Siltstone: Consists of silt-sized grains (between 0.0039 mm and 0.0625 mm in diameter). This is finer than sand, but coarser than clay.
* Shale: Formed from clay-sized particles (smaller than 0.0039 mm). Shale is often characterized by its ability to split into thin layers, called laminations.
Other factors can influence the final classification:
* Composition: The specific minerals present in the rock can also help in classification.
* Cements: The type of cement holding the grains together can be important.
* Fossils: The presence of fossils can be used to determine the age and environment of deposition.
Remember, these classifications are based on a continuum of grain sizes, and there can be overlap between categories.
