* Weathering and Erosion: Mountains are constantly being broken down by weathering (rain, wind, ice, etc.) and erosion. This process can turn rock into smaller particles, including clay.

* Sedimentation: The clay particles that are created can then be carried by water or wind and deposited in valleys or lower elevations. Over time, these deposits can build up to form layers of clay.

* Geological Formations: Some mountains formed from sedimentary rocks, which can include layers of clay. These layers can be exposed as the mountain erodes.

Examples:

* Claystone Mountains: Some mountains are composed primarily of claystone, a type of sedimentary rock formed from compressed clay.

* Clay in Mountain Soils: Mountains often have soils that contain varying amounts of clay, which can be important for plant growth and water retention.

* Clay Deposits in Mountain Valleys: Valleys at the base of mountains often have deposits of clay that have been transported down from the slopes.

So, while mountains aren't entirely made of clay, they can contain significant amounts of clay, both within their structure and in surrounding areas.