GEO 102 1st Edition Lecture 15 Outline of Last Lecture I Half lives Outline of Current Lecture II Physical Weathering III Chemical Weathering IV Erosion V Environments of Deposition Current Lecture Types of Physical Weathering Frost wedging ice gets into a crack of a rock expands and breaks the rock Unloading exfoliation Biological from tree roots and fungi Current glacial Thermal effects Types of Chemical Weathering Dissolution dropping acid o minerals It dissolves the mineral away Hydrolysis electrochemically plucking molecules of a mineral out of the mineral Oxidation oxygen displacing a portion of the molecules in metal rich rock o Clays do not form initially as clay Clay minerals only form as the residual broken down stuff of another mineral breaking down Erosion The transport of materials weathered from a rock The principle agents are o Liquid water the most common o Ice rare but very effective o Wind only small particles Entrainment These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute This refers to the act of lifting a particle from a position of rest to be carried in a wind or current We can predict how this will happen with great precision using math Order of Transport Heavy particles need a lot of energy to lift and carry Clay needs a lot of energy to lift van der waals forces but very little to carry it Particles are lifted in the following order o Silt sand pebbles and clay last But they are dropped in a different order o Pebbles sand silt and clay Why is the Beach Sandy This illustrates why different sediments are found in different places This is also a way we can know what past earth environments were like o Depositional environments o Certain rocks are associated with each Erosion Methods High energy versus low energy o Ice is slow but viscous so it is high energy o Wind is fast but not viscous so it is low energy o Water is the most common carrier Remember that the particles get further eroded as they travel and become smaller and rounder Environments of Deposition Energy also defines where things drop out o Beaches have lots of wave energy o It washes away the small particles sometimes even sand o Leaving only the heavy materials behind Example mud puddles and gold panning
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