A cliff itself isn't a type of erosion, but rather a landform formed by erosion.

Here's how cliffs are formed:

* Erosive forces like waves, wind, rain, and glaciers wear away the land over time.

* This differential erosion occurs when some rock types are more resistant to erosion than others.

* The less resistant rock is eroded faster, creating a steep drop-off called a cliff.

So, to answer your question more directly:

* Coastal Cliffs are primarily formed by wave erosion

* River Cliffs are formed by river erosion

* Glacial Cliffs are formed by glacial erosion

* Wind-Eroded Cliffs are formed by wind erosion

Let me know if you'd like to know more about any of these types of erosion!