The mechanical weathering of rocks like shale and sandstone causes their grains to break up over time and become sand and clay particles. Rocks that are constantly bombarded by running water, wind, and other erosion agents, will weather more quickly.

The most common sedimentary rock is shale. It is made of compressed mud–that is, a mixture of clay and silt (fine particles of mineral matter). The sand or gravel particles in sandstone and conglomerate are held together by a mineral cement.

This weathering breaks the rocks down into clay minerals and other small particles which often become part of the local soil. If undisturbed and buried, this accumulation of mud might be transformed into a sedimentary rock known as “mudstone.” This is how most shales are formed.

Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.

Slate is the metamorphosed form of the sedimentary rock called shale. However, it is much harder than shale and breaks with sharp edges.

Both limestone and mudstone/shale can ve very fine grained, so how do you tell them apart? Well, shales tend to break into thin, angular pieces whereas limestones tend to break into hard blocks. While mudstones also break into blocky pieces, they tend to be quite soft.

Arkose, coarse sandstone (sedimentary rock composed of cemented grains 0.06–2 millimetres [0.0024–0.08 inch] in diameter) primarily made up of quartz and feldspar grains together with small amounts of mica, all moderately well sorted, slightly worn, and loosely cemented with calcite or, less commonly, iron oxides or …

At the end of a glacier, where ice is melting as fast as it is being supplied from upstream, the sediments are deposited in a terminal moraine, a ridge of poorly-sorted glacial till. Thinner depostits of glacial sediments called a ground moraine or till plain are found behind the terminal moraine.

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