The Polarity of the Earth's Magnetic Field in the Geologic

question 18

Multiple Choice

The polarity of the Earth's magnetic field in the geologic past is

• A) unknown,but is assumed to have been identical to today's.
• B) known to have stayed constant through geologic time,as shown by remnant magnetization of iron-rich minerals in rocks.
• C) known to have experienced numerous reversals,as shown by remnant magnetization of iron-rich minerals in rocks.
• D) known to have stayed constant through time,based on theoretical calculations.

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Definitions:

Rock Characteristics

The inherent properties and features of rock, including texture, mineral content, and permeability among others.

Angular Clasts

Angular clasts are pieces of rock that have sharp edges and points, indicating they have not been traveled far from their source because they have not been significantly worn down by erosion.

Breccia

A type of rock consisting of angular fragments of minerals or rocks cemented together by a finer-grained matrix, often formed by volcanic or tectonic actions.

Formation

A rock unit that is distinct, laterally traceable, and mappable; also used as an informal term for an eroded, perhaps unusually shaped, mass of rock.