Geomorphology Chapter 2 Basic concepts 1 Chapter 2 Basic concepts Fundamental principles Geomorphic process Evolution of landforms Geologic structure Sound familiar structure process time 2 Geomorphic agents and processes Agent Process es running water erosion deposition waves erosion deposition groundwater dissolution precipitation volcanism emplacement of lava ash tectonism uplift deformation gravity mass wasting ice erosion deposition wind erosion deposition 3 Geomorphic processes cont Agent Process es Constructive Destructive running water erosion deposition waves erosion deposition groundwater dissolution precipitation volcanism emplacement of lava ash tectonism uplift deformation gravity mass wasting ice erosion deposition wind erosion deposition 4 Chapter 2 Basic concepts Geomorphic systems uniformitarianism equilibrium positive feedback 5 Chapter 2 Basic concepts Geomorphic systems uniformitarianism present is the key to the past especially useful for interpreting landforms that develop over long periods of time or relict landforms example glacial landforms 6 Chapter 2 Basic concepts Geomorphic systems equilibrium geomorphic systems are in balance If the balance is disturbed the system will adjust to a new balance equilibrium 7 Chapter 2 Basic concepts Geomorphic systems equilibrium analogous to principle of chemical equilibrium a A b B c C d D 8 Types of geomorphic equilibria 9 Chapter 2 Basic concepts Geomorphic systems equilibrium classic example graded stream 10 Graded Stream Slopes of streambeds are adjusted graded to amount of water Q and sediment load being carried by stream Q load Slope f Q load 11 Graded Stream What if sediment load is increased how will stream respond Why might load increase Q load slope f Q load 12 Graded Stream Initially additional sediment is too much for original slope to transport so deposition occurs load is increased 13 Graded Stream But deposition has effect of increasing slope new load old load new Slope f Q new load 14 Graded Stream Increased slope speeds up water increases discharge Eventually stream develops capacity to transport the additional sediment load new load A new equilibrium is reached old load new slope f new Q new load new Q old Q 15 Graded Stream What if sediment load is decreased how will stream respond Why might load decrease Q load slope f Q load 16 Graded Stream Initially original slope provides more water velocity than necessary to transport reduced sediment load so erosion occurs new load old load Q load 17 Graded Stream Erosion has effect of decreasing slope so water velocity and discharge are reduced Eventually stream adjusts to the reduced sediment load A new equilibrium is reached new load old load new slope f new Q new load new Q old Q 18 Which type of equilibrium corresponds to previous example 19 Chapter 2 Basic concepts Geomorphic systems positive feedback magnification of change in the direction of the initial adjustment example meander bend in river 20 meander bends maximum velocity maximum erosion maximum velocity maximum erosion 21 22 23 Rio Madre de Dios Amazon rain forest 24 In class exercise Graded Stream What if discharge Q is increased decreased how will stream respond Why might Q increase decrease Q load slope f Q load 25