On 31 Jan 08, at 9:09, J.E. Shields wrote: > Clays can adsorb ions on their surfaces and can absorb [sic; ITYM > "adsorb"] ions internally. Not all clays. Lateritic clays have very poor adsorption powers, hence the poor soils in the Oregon Coast Range (Ref: Roadside Geology of Oregon), Africa, and the Amazon Basin. For those of you on the Left Coast, there's a very nice exposure of bright red lateritic soil on the east side of I-5 a little north of Grass Pants, Oregon. Just a small cut with some erosion that exposes the subsoil, but quite prominent because of the brilliant color. -- Rodger Whitlock Victoria, British Columbia, Canada Maritime Zone 8, a cool Mediterranean climate on beautiful Vancouver Island