Select a Letter to view the associated terms.
C D E
F G H
I J K
L M N
O P Q
R S T
U V W
X Y Z
| Ultimate phalange
||The last digit.
| Ultramafic rock
||An igneous rock composed entirely of ferromagnesian minerals.
| Ultraviolet radiation
||That part of the electromagnetic spectrum ranging in wavelength from 0.2 to 0.4m m. Just past the visible violet spectrum.
| Unconfined aquifer
||An aquifer with no confining geologic structure on the aquifer (aquifer pressure about the same as atmospheric pressure).
||A discontinuity in the succession of rocks, containing a gap in the geologic record. A buried erosion surface. See also nonconformity.
||Loose earth material such as gravel, sand, or lava that hasn't solidified yet.
||a term that refers to hoofed animals. This includes Family Cervidae (deer) and Bovidae (sheep and goats) as well as the pronghorn. They typically have antlers or horns and are herbivores.
||The theory that geologic events in the past were caused by natural processes which are operating at the present time.
| Unsaturated zone
||The zone below the surface and above the water table, in which pore spaces are usually filled with air. Synonymous with phreatic zone.
||A structurally high area in the crust, produced by movements that raise the rocks, as in a broad dome or arch.
||An arched or uplifted segment of the crust. Synonymous with uplift.
||A rod-like bone composed of fused tail vertebrae, present in frogs and toads (Halliday 1987).
| U-shaped valley
||A valley with a U-shaped cross-section caused by glacial erosion. Contrast with the V-shape of a typical stream valley.
||the hollow muscular organ in female mammals in which the fertilized ovum usually becomes embedded, and in which the developing embryo and fetus are nourished (Morris 1992).