Geosphere Lecture 2 0.0 / 5 ? GeographyGeosphereUniversityNone Created by: P GREENWOODCreated on: 30-12-16 12:16 Mass cannot be created or destroyed 1 of 22 Change in Land surface elevation= amount of uplift or subsidence + balance between sediment supply and removal 2 of 22 Height change due to erosion= Volume removed/surface area 3 of 22 Qs= Volumetric sediment transport rate 4 of 22 Annual change in height of bed due to sediment movement QS(IN) – QS(OUT)/ River bed area 5 of 22 Landscape are in equilbrium when they experience no net change in form (elevation) over time (Uplift=Denundation) 6 of 22 Want must be specified to identify equilbrium time and space scale of interest 7 of 22 Long term equilbrium evolution of mountains Uplift=Erosion (Davis would argue this is not true) 8 of 22 Hack's concept of ........... equilbrium Dynamic 9 of 22 What time frame does Dynamic Equilbrium happen over (hack concept) 10 to power 4 years 10 of 22 What time frame does steady state equilbrium happen over (hack concept) 10 to power 2 11 of 22 What time frame does static equilbrium happen over (hack concept) 10 power minus 1 12 of 22 GK Gilbert pioneered the concept of mutual adjustment between form and process towards equilbrium 13 of 22 When did the quantative revolution happen mid 20th century 14 of 22 Power law is the process law which explains landscape form 15 of 22 How are power laws plot straight lines on graphs that have logarithmic axes without logarithmic axes they appear as curvess 16 of 22 Diffusive processess: landslides and soil creep (sediment momvemnt due to surface gradient) 17 of 22 Advective processess: seidment movment by water-driven processess (water and rainsplash) 18 of 22 Topographic changes during landscape evolution often lead to strong negative feedbacks because An imbalance between sediment supply and sediment removal at a point in the landscape leads to changes in surface height and slope 19 of 22 For a hillslope in equilibrium (ie where uplift = erosion) qS increases down slope 20 of 22 Upper half of slope: qS increases down slope S must also increase down slope 21 of 22 Lower half of slope: qS increases down slope qW increases down slope (K >1 and M >1) S must decrease down slope 22 of 22
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