Geologic dating issues

Today, few discussions in geology can occur without reference to geologic time and plate tectonics.

They are both integral to our way of thinking about the world.

Dating from the Cambrian through Devonian periods (542-359 million years ago), these are the oldest rocks exposed in the plateau country.

The plateaus, which are actually the flattened bottoms of giant folds of rock, preserve younger rocks from the Mississippian and Pennsylvanian At the base of the Mississippian-Pennsylvanian section is a distinctive black shale, the Chattanooga Shale, which dates to the Devonian.

in the northwest corner of Georgia, Sand, Lookout, and Pigeon mountains belong to the geologic province known as the Appalachian, or Cumberland, Plateau.

This plateau extends continuously from New York to Alabama and forms the western boundary of the Appalachian Mountains.

You know, for example, that the First World War came before the Second World War, but how long before?

Was it tens, hundreds or even thousands of years before?

As Holmes, writing in Nature in 1913, put it: "the geologist who ten years ago was embarrassed by the shortness of time allowed to him for the evolution of the Earth's crust, is still more embarrassed with the superabundance with which he is now confronted." It continued to be hotly debated for decades.

Cherry Lewis commented, "In the 1920s, as the age of the Earth crept up towards 3 billion years, this took it beyond the age of the Universe, then calculated to be only 1.8 billion years old.

In 1911 the discovery that the world was billions of years old changed our view of the world forever.

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