Upper left and right: White weathering rinds formed on red granite due to the process of calcification. The rocks were collected from Mt. Monster, southeastern South Australia, by Professor Charles Rowland Twidale of the University of Adelaide. Bottom left: Weathering rind with a thick transitional layer (referred to as a leached layer or a dissolution layer) formed on andesite gravel. Bottom right: Weathering rind on Sanukite (high-magnesian andesite). Thickness of the white layer affected by leaching, which exists just inside the brown layer affected by oxidation of iron, tends to decrease in rocks with low porosity.
(Photograph & Explanation: Chiaki T. OGUCHI)
2017 Tokyo Geographical Society