Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes 2Landforms and exogenetic processes

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes 2.1 When will a river appear?

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes Exogenetic processes Exogenetic processes What are exogenetic processes? Besides endogenetic processes, are there any other processes that shape the earth?

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes What are exogenetic processes? Exogenetic processes are the processes generated by agents, such as _______, ______ and ____. riverswindice They bring down materials from mountains which fill the valleys. Let’s take rivers as an example.

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes What are exogenetic processes? The two main processes are: Denudation Deposition Weathering Mass wasting Erosion Transportation Deposition

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes Before studying the exogenetic processes that the river produces, let’s see how water moves on the earth!

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes Where does the water mainly store on the earth? In what ways does water move on our earth? Atmosphere Rivers/ lakes Vegetation Ocean Soil/ rocks Evaporation Transpiration Evapotranspiration Condensation Precipitation Surface run-off Infiltration Subsurface run-off

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes In what ways does water move on our earth? Through the water cycle, water moves on our earth. Let’s look at it in detail.

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes Unsaturated rock and soil Water table Saturated rock Impermeable rock Precipitation Interception by vegetation In what ways does water move on our earth? Stem flow Drip flow Evaporation Transpiration

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes Precipitation Overland flow Channel flow Surface run-off Evaporation In what ways does water move on our earth?

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes Unsaturated rock and soil Water table Saturated rock Impermeable rock Surface storage Infiltration Soil moisture storage Ground water storage Percolation Throughflow Base flow Subsurface run-off Absorption Evaporation In what ways does water move on our earth?

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes What can we find in a river basin? What is a river basin? River basin is an area drained by a main river with its ___________ and _____________. tributaries distributaries Can you identify different features in a river basin? Its boundary is known as the __________. watershed River source Tributary Confluence points Main river Mouth of the river Distributaries Watershed

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes 1Denudation Weathering Rocks are weakened or broken down in the original place because of _________, changing ____________ and ________________. The broken rock pieces are called ____________. rock debris moisture temperatureliving organisms

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes 1Denudation Mass wasting Weathered materials The debris is brought down slope by _______. gravity

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes 1Denudation Erosion Loosened materials are removed. River

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes 1Denudation Transportation Weathered and eroded materials are carried away to other areas. Please click below to view footage Look at the sand and the stones carefully. What can you find from the footage? They are carried away by water to other areas!

Part 2 Quit © Oxford University Press 2006 Landforms and exogenetic processes 2Deposition The eroded materials rest on the ground that the river carries or on the _________. river bed