1. Question: If cratering rate on Earth is same as our Moon, why are their so few craters preserved? Answer: Erosion

8. Estimating natural erosion rates Accumulation of sediment versus time in alluvial fans. Ratio of cosmogenic isotopic creation rate/unit area to concentration/unit volume of sediments. Closure age of exposed minerals at surface plus increase of temperature with depth.

9. Erosion Rate for Cascades ~ 0.05 –.25 Km/Ma mm/y = m/Ka = Km/Ma

10. Erosion Rate for Central France: 55 m/MA

11. 1 t/ha/y => 30 m/Ma

15. 1 mm/a = 1km/Ma

16. Summary of Erosion rates Himalaya: 2-3 m/Ky = 2-3 km/Ma Eastern edge of Bolivian Altiplano: 3 km/Ma Cascades: 300 m/Ma Massif Central (France): 50 m/Ma Atacama Desert (Chile/Peru): 0.5 m/Ma Central Australia: 0.5 m/Ma

17. Question If erosion can flatten mountain topography in only a few million years, why are there mountains at all?

18. Question: If erosion can flatten mountain topography in only a few million years, why are there mountains at all? Answer: Uplift is continuous Implication: Earth is a dynamic planet

24. L = cA ½ Channel length and drainage area

25. Streamflow and drainage area… River basins in Kentucky, USA, from Solyom and Tucker, 2004 Q = 0.0171* A 0.9932 R 2 = 0.9977 or

26. Channel Width: Data from the Clearwater River, Washington State, from Tomkin et al., 2003. Q = 0.1335 * A 0.9 W =4.2* A 0.42

27. W = b(AP) ½ Should actually be discharge = Area x precipitation

31. Spatially Variable Precipitation, Ellis, Densmore & Anderson, 1999 Precip Distance