Index fossils, horizontality, intrusion

Front

What are index fossils?

Back

Index fossils are fossils of organisms that were widespread but only existed for a short period of geological time. They are used to date and correlate the age of rock layers.

Front

What are the two main traits of the best index fossils?

Back

The best index fossils are widespread geographically and have a short lifespan.

Front

What does the principle of original horizontality state?

Back

The principle of original horizontality states that layers of sediment are originally deposited horizontally under the action of gravity.

Front

What is an intrusion in geology?

Back

An intrusion is a body of igneous rock that forms when magma pushes into existing rock layers and solidifies.

Front

How can you determine the relative age of rock layers?

Back

You can determine the relative age of rock layers by using principles such as superposition, original horizontality, and cross-cutting relationships.

Front

What is the significance of finding the same index fossil in different locations?

Back

Finding the same index fossil in different locations indicates that the rock layers containing those fossils are of the same age.

Front

What is a fault in geological terms?

Back

A fault is a fracture or zone of fractures between two blocks of rock, which can cause displacement.

Front

What does the principle of superposition state?

Back

The principle of superposition states that in an undeformed sequence of sedimentary rocks, the oldest layers are at the bottom and the youngest layers are at the top.

Front

What is the difference between a fault and an intrusion?

Back

A fault is a break in the Earth's crust where rocks have moved past each other, while an intrusion is molten rock that has solidified within existing rock layers.

Front

What is the role of index fossils in dating rock layers?

Back

Index fossils help geologists determine the relative ages of rock layers and correlate them across different geographic locations.