Questions and Anwers from
Geologist Frank Ettensohn
Why is Kentucky like the Bahamas?
Because 350 million years ago Kentucky was a basin filled with shallow, warm water (like the Bahamas) and we can still find the brachiopods (fossils) all over Kentucky to prove it.
Kentucky has many limestone rocks with animals preserved as fossils. These animals were originally marine animals from warm, shallow water--just like the Bahamas now.
How do you know how old rocks are?
The easiest way to date rocks is look at the type of fossils in the rock and compare that to what scientists have already decided was going on at that time.
If rocks don't contain fossils then geologists have dated specific types of rocks radiometrically. We carry that information to this--using correlation and inference. Volcanic ash is used to date rocks that contain things that were current at the time of the volcanic event.
How did you know you wanted to be a geologist?
I used to find fossils as a kid when I grew up outside Cincinnati, Ohio. My mother used to let us look for rocks while she shopped.
What does studying rocks tell us?
Rocks tell us about the history of the earth. Each layer is like a page in a book--if you know the language you can read the book. Rocks show you environmental change through time. Remember, The present is the key to the past.
How do rocks help us today?
Rocks are important to our ecomonics because oil and coal are found in rocks. Other rocks are important building products. Limestone is used in road construction, steel-making, concrete and cement.
Why do geologists taste rocks?
It's an easy way to find the presence of silt, which in some cases is too fine to be felt by hand. Silt helps identify rocks. It tastes gritty...don't taste too much, you only need a little!
What is the difference between a mineral and a rock?
A mineral is a naturally occurring substance with a definite chemical structure. A rock is a naturally occurring combination of minerals cemented together.
Do you have a favorite rock?
My favorite rock at the Pound Gap outcrop has a lot of brachiopod fragments. There are so many I call it "brachiopod hash!"
Is there coal at Pound Gap?
There isn't much coal at Pound Gap.