Chapter'6: Weathering and Soils
Chapter 6: Weathering and Soils
Introduction: Weathering The breakdown of rock At the earth's surface, rocks are exposed to the effects of weathering: the chemical alteration and mechanical breakdown of rock, when exposed to air, moisture and organic matter Weathering is an integral part of the rock cycle Weathering converts rock to regolith
Introduction: Weathering— The Breakdown of Rock ◼ At the Earth’s surface, rocks are exposed to the effects of weathering: the chemical alteration and mechanical breakdown of rock, when exposed to air, moisture, and organic matter. ◼ Weathering is an integral part of the rock cycle. ◼ Weathering converts rock to regolith
Weathering profile
Weathering profile
Physical Weathering Rocks break at weak spots when they are twisted, squeezed, or stretched by tectonic forces Such forces form ioints Rocks adjust to removal of overlying rock by expanding upward Removal of the weight of overlying rocks releases stress on the buried rock and causes joints to open slightly, thereby allowing water, air, and microscopic life to enter
Physical Weathering ◼ Rocks break at weak spots when they are twisted, squeezed, or stretched by tectonic forces. ◼ Such forces form joints. ◼ Rocks adjust to removal of overlying rock by expanding upward. ◼ Removal of the weight of overlying rocks releases stress on the buried rock and causes joints to open slightly, thereby allowing water, air, and microscopic life to enter
Joints a Joints occur as a widespread set or sets of parallel fractures When dikes sills lava flows and welded tuffs cool they contract and form columnar joints joints that split igneous rocks into long prisms or columns)
Joints ◼ Joints occur as a widespread set or sets of parallel fractures. ◼ When dikes, sills, lava flows, and welded tuffs cool they contract and form columnar joints (joints that split igneous rocks into long prisms or columns)