Assertion: sill | /r/HasProperty | formed
Facets:
value: mostly
type: DEGREE
value: underground
type: LOCATION
Source sentences:
text: Dykes form when the point of origin is beneath the forming dyke, while sills are formed when the starting point is either on the left or right side.
text: Although sills can become exposed, sills are formed underground and are thus composed of plutonic igneous rocks .
text: • Mostly a sill is formed when a dike cannot go up further and starts to move horizontally.