dating exposed ary news - 6 rules of relative age dating

Hutton's discovery was a very important event in geology!Hutton determined that the rocks were deposited over time. Hutton knew that deposition and erosion are very slow.So, many of the names of the time periods are from places in Europe. Apply laws of stratigraphy to explain the rock formation below. Which rock in the photo below formed first, the igneous rock (A) or the sedimentary rock (B)? The law of superposition determines which rock layers are younger or older than others.

6 rules of relative age dating-5

The rock is so soft that the Channel Tunnel connecting England and France was carved into it! For example, a key bed from around the time that the dinosaurs went extinct is very important. This unusual clay layer has been used to match rock up layers all over the world.

Like index fossils, key beds are used to match rock layers. A thin layer of clay was deposited over much of Earth’s surface. It also led to the hypothesis that a giant asteroid struck Earth and caused the dinosaurs to go extinct.

A gap in the sequence of rock layers is called an unconformity. Hutton saw that the lower rock layers are very old. There are no layers in between the ancient and recent layers.

Hutton thought that the intermediate rock layers eroded away before the more recent rock layers were deposited.

Many of the divisions mark major events in life history.

Divisions in Earth history are recorded on the geologic time scale.

Erosion may have worn away some of the rock, but layers on either side of eroded areas will still “match up.” Look at the Grand Canyon in Figure below. You can clearly see the same rock layers on opposite sides of the canyon.

The matching rock layers were deposited at the same time, so they are the same age.

Sediments were deposited in ancient seas in horizontal, or flat, layers.

If sedimentary rock layers are tilted, they must have moved after they were deposited.

He realized that for both to occur would take an extremely long time. What evidence is used to match rock layers in different places? They may be found on more than one continent or in more than one country.

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