A mesa or butte, Ngura in the local indigenous language, is a small isolated flat-topped hill with steep sides. Mesa and Buttes form by weathering and erosion of horizontally layered rocks. Variations in the ability of different types of rock to resist weathering and erosion cause the weaker types of rocks to be eroded away, leaving the more resistant types of rocks higher than their surroundings. To form a mesa or butte requires a hard erosion resistant caprock.
In differentiating mesas and buttes, geographers use the rule of thumb that a mesa has a top that is wider than its height, while a butte has a top that is narrower than its height. The word mesa is Spanish, Portuguese and Sardinian for "table". The word butte comes from a French word meaning "small hill".
Earthcache Tasks. At the list coordinates you are standing at the base of a small hill. Please submit answers for the following questions to the cache owner.
- Is the small hill a mesa or a butte? How do you know?
- Find a piece of the caprock. Compare this mineral to the base of the hill. Hardness, colour, texture?