Regions of the Earth's surface where limestone is exposed and abundant are called karst landscapes.

Here's why:

* Karst is a term used to describe a distinctive topography formed by the dissolution of soluble rocks, primarily limestone.

* Limestone is a sedimentary rock primarily composed of calcium carbonate, which is easily dissolved by acidic water.

* The dissolution process creates a variety of unique features like caves, sinkholes, underground rivers, and dry valleys, all of which contribute to the characteristic landscape.

So, while limestone itself is the rock type, karst is the term used to describe the landscape shaped by its dissolution.