WEATHERING EROSION SOIL FORMATION WEATHERING EROSION Most rocks

WEATHERING, EROSION, SOIL FORMATION

WEATHERING + EROSION Most rocks = formed underground w/ intense heat + pressure When exposed @ surface rock breaks down § Weathering § Erosion Both return chemical elements back to crust § Deposition happens via the hydrologic cycle § Without this part of the rock cycle no elements ever recycled

WEATHERING Physical Mechanical Breakdown § § Water Wind Freeze-thaw cycles Roots Overall, it exposes more rock and makes it more vulnerable to more degradation Is this positive or negative feedback?

WEATHERING Chemical Releases essential nutrients § Then available for use is plants and other organisms Most important on newly exposed rock (called primary minerals)

WEATHERING Chemical + Humans Some is the result of human activity: Sulfur Dioxide (SO 2) released when fossil fuels combust and reacts with H 20 to form an acid = Acid precipitation § Premature weathering of statues, grave stones, etc. Good or Bad? Natural or due to acid precipitation can contribute extra nutrients to an ecosystem…(hmm? ) Affects soil fertility § Nutrients vs. acid tolerance Weathering of granitic rocks consumes CO 2…may reduce atmospheric carbon dioxide

EROSION Badlands, SD

EROSION Good or Bad? Physical removal of rock fragments § Wind, water and ice do this § Burrowing organisms contribute An accumulation of eroded material (sediment, rock, soil) = deposition Natural Process: streams, glaciers, and wind-borne sediments continually carve, scour, and grind Poor human land use contributes substantially: Deforestation, overgrazing, road building and unmanaged construction …eroded material eventually deposited and can cause additional environmental problems.

NOW… So far we’ve covered two parts of the Geologic cycle § the tectonic cycle § and the rock cycle… § The third part—soil formation—takes place at the Earth’s surface.

SOIL Soil Formation A mix of geologic and organic compounds Dynamic membrane Connects overlying biology with underlying geology Ecosystem services provided by soils:

Soil and AG Vocab Soil and Rock 2004 FRQ § Question 4 answer A FEW RESOURCES