The district of the United States in which tornadoes are most frequent; it encompasses the great lowland areas of the central and upper Mississippi, the Ohio, and lower Missouri River valleys.
See pack ice.
The middle subdivision of Proterozoic geologic time. Also known as Penokean; Upper Huronian.
Lizard stone is a kind of serpentine from near Lizard Point, Cornwall, England, used for ornamental purposes.
A natural, brown to jet black paraffin wax occurring in irregular veins; consists principally of hydrocarbons, is soluble in water, and has a variable melting point. Also known as ader wax; earth wax; fossil wax; mineral wax; native paraffin; ozokerite.
In geology unconformability describes a want of parallelism between one series of strata and another, especially when it is due to a disturbance of the position of the earlier strata before the latter were deposited.
Fractures that are developed over large areas of the earth’s crust with relatively little change in orientation, that show no evidence of offset across the fracture plane, and that are always perpendicular to major bedding surfaces. They are commonly developed in orthogonal sets.
A lenticular rock formation encountered unexpectedly in drilling an oil or a gas well; it differs from an adjacent persistent formation in lithology and hardness.
Method of mass spectrometry using ions that are produced by heating and ionising sample material.
A body of igneous rock that is more or less vertical and cylindrical; it crosscuts adjacent sediments.