Often the spheroidal weathering, which created these corestones and the enclosing saprolite occurred in the prehistoric past during periods of humid, even tropical climates.
22.
When saprolite is exposed by physical erosion, these concentric layers peel ( spall ) off as concentric shells much like the layers of a peeled onion.
23.
Saprolite ( from Greek ?????? = putrid + ????? = rock ) is a chemically weathered rock ( literally, it means " rotten rock " ).
24.
Within saprolite, spheroidal weathering often creates rounded boulders, known as " corestones " or " woolsack ", of relatively unweathered rock.
25.
In the Australian deposits, chrysoprase occurs as veins and nodules with brown goethite and other iron oxides in the magnesite-rich saprolite below an iron and silica cap.
26.
For instance, earthquakes in the region can cause cracks in the hard, upper layer of laterite, which allows water to seep into the more porous layer of saprolite underneath.
27.
This led to severe chemical weathering of the granite to saprolite rich in kaolin clays, decomposed from the large visible crystals of potassium feldspar that are so conspicuous in the granite.
28.
Pedology; A is the topsoil; B is a regolith; C is a saprolite, a less-weathered regolith; the bottom-most layer represents the bedrock . ]]
29.
Among the natural controls on lavaka formation are the amount of seismic activity in the region, the topographic relief ( or slope ), and hydraulic conductivity of materials in the saprolite.
30.
Soil layers, from soil down to bedrock : A represents soil; B represents laterite, a regolith; C represents saprolite, a less-weathered regolith; below C is bedrock
