Relative rock layers

Scientists use relative dating to arrange geological events, and the rocks they leave behind, in a sequence. The method of reading the order is called stratigraphy (layers of rock are called strata).

Check out this cliff. It looks as though one group of layers was tilted and eroded away before new rocks were formed on top. Help us work out the relative ages of the layers of sedimentary rocks, from youngest to oldest. Remember that the younger sedimentary rocks lie on top of older ones and were horizontal when formed. It's recommended that you watch this animation before you use the interactive. Remember to hover your mouse over the text labels for more information about the rock layers.

Drag and drop the text labels next to the layer you think is being described. If you want to redo an answer, click on the box and the answer will go back to the top so you can move it to another box. If you want to check your answers, use the reset incorrect button, which will reset incorrect answers only. When you are satisfied with your selection, use the check answers button to check them. Reset all to practise again from the start.

This interactive is part of the Rock layers and relative dating activity.

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Label

Description

youngest rock pre-tilt

This was the last layer to be formed before the rocks tilted.

oldest rock pre-tilt

This rock layer is below all the others.

youngest rock post-tilt

This is the youngest rock above all the others.

second-oldest rock

This rock layer is just above the oldest.

thinnest rock

This is the thinnest rock layer.

oldest rock post-tilt

This layer formed on top of earlier rocks after they were tilted and eroded away.