The mountain or hill formed around a crack in the Earth's crust is called a horst.

Here's how it happens:

* Faulting: The crack in the Earth's crust is called a fault. When tectonic plates move, they can cause the rocks along these faults to break and shift.

* Uplift: In a horst, the rock block between two faults is pushed upwards. This creates an elevated area that stands out from the surrounding land.

* Graben: The opposite of a horst is a graben. In a graben, the rock block between two faults is pulled downwards, creating a valley or depression.

Examples:

* The Basin and Range Province in the western United States is a classic example of horst and graben formations.

* The Rhine Valley in Europe is a graben, with the surrounding mountains being horsts.

Let me know if you have any more questions!