How Do Rock Layers Change?

The diagram shows some rock layers. Which of these most likely caused the feature labeled X in the diagram?

• earthquake

• erosion

• landslide

• volcano

Devon wants to know if the rock he found is older than the rock Sue found. Which step will not help Devon find his answer?

• Compare the weight and size of each rock.

• Decide the relative age of Devon’s rock to Sue’s rock.

• Count the number of rock layers above the layer where Devon found his rock.

• Compare the location where Devon found his rock to where Sue found her rock.

A rock layer on the side of a cliff looks bent. The rock layer looks like a wave. Which of these most likely caused this?

• earthquake

• moving glacier

• wind and water

• heat and pressure

After examining the rock layers in one place, a class hiked a mile away and looked at another set of rock layers. How can they determine if these rock layers are the same age as those at the first location?

• By picking random fossils and comparing them with those at the first location

• By comparing the rock types from both locations to see if they are the same

• By trying to match all the rocks and fossils with those at the first location

• By using a rock guidebook to identify the rock types and then match them to the layers

Raj places three newspapers flat in a box. He places a pebble on the top newspaper. Raj places three more newspapers on top of the pebble. He finishes by placing a different pebble on the very top layer of newspaper. What is Raj most likely demonstrating?

• How a fault forms underground

• How a canyon forms in rock layers

• How to determine the relative ages of the rocks

• How rocks move from deep in the earth to Earth’s surface

A scientist is studying a cliff by the ocean. There are five rock layers visible in the cliff. She finds a rock layer with shells in it. The scientist knows that the rocks on the bottom layer of the cliff are 150 million years old. The top rock layer is 1 million years old. Describe the age of the three rock layers between the bottom and the top layers.

Answer explanation

The three middle rock layers will be between 1 million and 150 million years old. The rock

layers toward the bottom will be older than the rock layers towards the top.

Explain how a river could change rock layers over time.

Answer explanation

A river could cut into rock layers, making a canyon and washing away the rock layer.