Diorite. An intrusive igneous rock composed of sodium-rich [feldspar] and dark minerals, with only small amounts of quartz.
Dip. The angle at which a layer of rock is inclined below the horizontal.
Dome. A roughly circular upfold in which the rock layers [dip] outward in all directions from the center.
Dowsing. Searching for underground water or ore with a divining rod, usually a forked stick supposed to locate spots where the desired substance may be found under the surface.
Echinoderm. One of a large group of marine invertebrate animals, most of which have pentagonal symmetry and a skeleton of many calcite plates. Many forms are spiny. The group includes starfish and sea urchins.
Evaporite. Chemical sediments precipitated when water (usually sea water) evaporates.
Extrusive rocks. [Igneous rocks] formed when molten rock material is ejected onto the surface. Synonymous with volcanic rocks.
Fault. A break in the rocks in which there has been displacement of the two sides relative to each other.
Fault block range. A mountain range bounded on two or more sides by [faults].
Feldspar. A group of light-colored aluminum silicate minerals that are major constituents of [igneous rocks]. They contain potassium, sodium, and calcium in differing proportions.