GEO 155 1st Edition Lecture 23 Last Lecture Glacial Landforms Outline of Current Lecture I Erosion on Slopes a Prelude to Erosion Weathering b Slope Erosion Processes c Links between Erosional Processes and Form i Simple Example ii Complex Example d Slides Current Lecture Weathering Physical weathering Break down into smaller pieces Frost shattering in environments with enough precipitation and temperature fluctuation above and below the freezing point of water allows liquid water to freeze in cracks of rock expands the rock s surface and breaks the rock Chemical weathering Involves a chemical alteration Solution of limestone dissolved by acids even slightly acidic rainwater creates rectangular cracks under the surface of the rock water passes through the cracks dissolving rock especially at the 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 intersections of the rectangles gradually opening up the rock collapsing it downward to form a sink hole Erosional Processes Sheet Erosion Soil particles carried downhill by overland flow Mass Erosion Material not carried by water Rapid rock fall landslide Slow creep o Water moves into soil swelling the surface or soil freezes and expands the surface particles lifted to new expanded level until the soil thaws and then gravity pushes the particle downhill from its original position Linkages Undercutting Weathering concentrated at base of the slope o Water wears away the bottom of the slope gravity causes rock fall leaving a steep clif o When a rock structures has layers of hard and soft rocks the soft rock layers erode quicker so the hard rock layers above break of making a steep clif with a staircase appearance Geomorphologist Schumm looked at the Badlands in South Dakota and noticed two types of structures 1 Straight slopes made of Brule formation rock type a Weathers into fine particles leading to i Overland flow ii Parallel sheet erosion evenly eroded b Occurs in arid and shallow soil vegetative areas 2 Convex shaped slopes of Chadron formation rock type a Weathers into coarse particles leading to i Infiltration ii Creep 1 Particles shift down to replace lost particles 2 Net concentration of erosion on top of slope b Occurs in denser humid areas 3 To measure the erosion Schumm drove metal stakes into the ground and found the distance of erosion to be even for Brule formation and more erosion toward the top of slopes in Chadron formation
View Full Document
Unlocking...