Formation of Impact Craters - Lunar and Planetary Institute
Formation of Impact Craters - Lunar and Planetary Institute
Formation of Impact Craters - Lunar and Planetary Institute
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30 Traces <strong>of</strong> Catastrophe<br />
Tectonism can also break up regions <strong>of</strong> original shocked rocks<br />
<strong>and</strong> disperse them as large discrete areas across the geological<br />
l<strong>and</strong>scape [e.g., the Beaverhead (Idaho) structure<br />
(Hargraves et al., 1990; Fiske et al., 1994)]. Sufficient tectonism<br />
<strong>and</strong> metamorphism could destroy even large impact<br />
structures or make them totally unrecognizable.<br />
Geologists must therefore be prepared to recognize impact<br />
structures in all states <strong>of</strong> preservation, from young, fresh,<br />
well-exposed circular structures filled with distinctive shocked<br />
breccias to older features in which distinctive shock effects<br />
are scattered, barely recognizable, or deeply buried. It is essential<br />
to be able to recognize the variety <strong>of</strong> distinctive shock<br />
effects associated with impact structures <strong>and</strong> to underst<strong>and</strong><br />
where different types <strong>of</strong> shock effects may be located in the<br />
original crater.
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