Abstract

Measurement of each size fraction with Munsell Color Chart shows that the saltating population (2 to 4.5phi ) has reddest, darkest, and most intense color, averaging 2.5 YR 4/7. Red color in these sands is caused by a hematitic clay cutan formed during Pleistocene lateritization, enhanced by aging, and covered over by a thin silica coat. A Holocene limonitic fluff occurs on top of the silica coat. Coarser grains are yellower because they have more yellow fluff and less red cutan; reg sediments are darker because they contain carbonaceous dots. With aging, sands change from yellow to red and become darker and less intensely colored because of a four-stage process: weathering to limonite, dehydration to diffuse hematite, recrystallization to hematite crystals, and green-darkening. Thus Holocene sands are orange, Pleistocene brick-red, and early Paleozoic dull liver color.

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