Clay 4 – Window to the Past
If you’re searching for a window to our environmental past, you might look no further than the ground beneath our feet – especially if there’s clay. I’m Jim Metzner and this is the Pulse of the Planet.
Schroeder: Clays are records of environmental change. There are several different types of clays that form in the environment. And if we can associate the types of clay in the types of environments we can make our way back into the geologic past, then we can tell whether the environment was wet or dry, and perhaps what types of organisms were living in association with the clays of the time.
Paul Schroeder is a professor of geology at the university of Georgia.
Schroeder: Geologists use the clays as kind of the key to the past. If you were to look at a clay in the modern forming environment, let’s say a desert or in a very wet tropical environment, those clays are distinctly different. And we can work her way back through the geologic record and use those clays as indicators of past environments.
This is how geologists reconstruct the climates of the geologic past by looking at the types of clay minerals that are preserved. What surprises us mostly is not so much how wet or how dry or how hot or how cold the earth has been through geologic time.
What what surprises geologists is sometimes is how quickly that those properties change on earth. Sometimes the transition from one clay type to the next can be little more abrupt than what we thought. That challenges us to finesse the question what caused that condition to change so quickly.
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