Rock Layers (Geologic Time)

A fossil is an imprint of something that lived a long time ago. I have seen an imprint of a shell on a rock.

Scientists can figure out what the rocks are made of and about different things that used to live there.

Dinosaurs, ferns, raptors, pterodactyls, woolly mammoths, different bug like things.

Weathering is when rocks are broken down into smaller pieces.

Erosion happens when wind and water move small pieces of rocks and stuff around and it settles in a new place.

Some processes that can change how the landscape looks are erosion, earthquakes, volcanoes, and landslides.

Earth is 4.6 billion years old and the geologic time scale is used to keep track of the events that have happened since Earth was formed.

A big meteor hit Earth, and scientists know this because they have found a rock layer they named the K-T boundary that show dinosaurs living before that layer but none after.

Weathering and erosion made things like the Grand Canyon because the river weathered the rocks and erosion moved it down the river.

The rock layers can tell us when different organisms went extinct. They can also tell us when new organisms showed up, like during the Cambrian explosion.

Sedimentary rock is made from sediment that were eroded and deposited in layers. Over time, the weight of the layers on top compact the sediments in the layer below. Sediments are later cemented together by natural processes forming sedimentary rock.

Earthquakes shake Earth, sometimes causing cracks. When Earth shakes, it moves the crust around and this could help expose new rock layers and fossils.