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The Age of the Earth - The Age of the Earth Radiometric age...

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The Age of the Earth Radiometric age assignments based on the rates of decay of radioactive isotopes , not discovered until the late 19th century, suggest the earth is over 4.5 billion years old. The Earth is thought older than 4.5 billion years, with the oldest known rocks being 3.96 billion years old. Geologic time divides into eons, eroas, and smaller units. An overview of geologic time may be obtained athttp://www.ucmp.berkeley.edu/help/timeform.html . Evolutionary Thought During the 1700s Swedish botanist Carl Linne (more popularly known as Linneus , after the common practice of the day which was to latinize names of learned men), attempted to pigeon- hole all known species of his time (1753) into immutable categories. Many of these categories are still used in biology, although the underlying thought concept is now evolution and not immutability of species. Linnean hierarchical classification was based on the premise that the species was the smallest unit, and that each species (or taxon) belonged to a higher category.
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