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.
Types of Rocks. There are three main types of rocks - igneous, sedimentary, and metamorphic. Igneous rocks are formed when melted rock (magma) cools and solidifies. Some igneous rocks are formed when the magma erupts from a volcano. Obsidian, basalt, and granite are all examples of igneous rocks.