Radiometric dating geologic time and the age of the earth

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These discoveries had a long-lasting influence on crystallography because they led to the development of the X-ray powder diffractometer, which is now widely used to identify minerals and to ascertain their crystal structure.Advanced analytic chemical equipment has revolutionized the understanding of the composition of rocks and minerals.

A year later William Bragg of Britain and his son Lawrence perceived that such a pattern reflects the layers of atoms in the crystal structure, and they succeeded in determining for the first time the atomic crystal structure of the mineral halite (sodium chloride).Experimental petrology also provides valuable data on the stability limits of individual metamorphic minerals and of the reactions between different minerals in a wide variety of chemical systems.These experiments are carried out at elevated temperatures and pressures that simulate those operating in different levels of Earth’s crust. Bridgman developed a technique for subjecting rock samples to high pressures similar to those deep in the Earth.This method has wide applications in, for example, the fields of industrial mineralogy, materials science, igneous geochemistry, and metamorphic petrology.Microscopic fossils, such as ostracods, foraminifera, and pollen grains, are common in sediments of the Mesozoic and Cenozoic eras (from about 251 million years ago to the present).

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