Lava that cuts through rock layers and then hardens to form a feature is called a dike.

Here's why:

* Dikes are vertical or near-vertical sheets of igneous rock that intrude into pre-existing rock layers.

* The lava that forms them cools and solidifies within the existing rock structure.

* They can be quite thin, but they can also be quite thick and extend for considerable distances.

Let me know if you have any other questions about geological features!