Medical Definition of amnesia. 1: loss of memory sometimes including the memory of personal identity due to brain injury, shock, fatigue, repression, or illness or sometimes induced by anesthesia a period of amnesia after the wreck.
Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call mud. This composition places shale in a category of sedimentary rocks known as mudstones.
The crust and the mantle contain different kinds of rocks making them chemically different. The upper mantle rocks are primarily peridotite. The crust contains of a variety of rocks. Igneous rocks, sedimentary rocks, and metamorphic rocks are the main categories of rocks found on the Earth's surface.