Spheroidal weathering
is a chemical process that occurs in large blocks of rock. Onion-like layers form as the joints of the rock wear away. The result is jagged layers of rock, rounded edges and a concentric-like weathering.
Causes
In large blocks of rock, the joints erode first. This allows water to penetrate the rock from all angles. The fragments left will be weathered along the edges, inside and outside, forming the onion-like erosion.
Process
Spheroidal erosion takes longer to occur than other types of erosion. At lower temperatures the process takes longer which is why granite mountain tops are jagged and not rounded.
Alabama Hills
Spheroidal weathering can be found here in the large 90 million year old granite rocks. Because the joints were eroded vertically, many of these rocks stand in rounded shapes.
Yosemite Park
The half dome in Yosemite Park is a large monolith said to be created by spheroidal weathering.
Exfoliation
Exfoliation has similar features to spheroidal weathering, but occur son a much larger scale. Spheroidal weathering is caused by a chemical process while exfoliation is caused by a mechanical process.
Tags: blocks rock, chemical process, large blocks, large blocks rock, Spheroidal weathering, takes longer, Yosemite Park
