A.  Origins
		• 1.  Weathering of parent rock material – chemical alteration, e.g.,: • H2O + CO2 --> H2CO3 --> H+ + (HCO3)- • actually uses up CO2 from atmosphere! – physical alteration, e.g.,: • grinding; freezing/thawing; erosion; transport • 2.  Deposition • 3.  Biotic interactions; further weathering