Chapter 18 PDF

Preview

Summary

Clark Monson's lecture notes from chapter 18 in Physical Geography (GEOG 101)...

Description

Chapter 18 Topography of Arid Lands Dry vs Humid Environments    



Weathering is mostly physical in dry climates Most mass wasting is rockfall in dry climates Soil easily erodes from lack of vegetation Drainage: streams are usually ephemeral or exotic o Ephemeral: temporary- running water after a thunderstorm or in the spring o Exotic: from a far away place Wind is important to shifting sand o Deflation: wind blowing sand around o Abrasion: blowing wind starts to wear down rocks

Five Prominent Desert Landscapes 

Erg o o o

“Erg” is Arabic for “sea of sand” Sand often accumulates into dunes Types of sand dunes:  Barchan dunes  Form where there’s not a lot of sand  They have little horns on the sides of the dunes  Crescent shaped- horns always point downwind  Windward side is not as steep as the leeward side  Transverse dunes  Form where there’s a lot of sand  Basically like interconnected barchan dunes  Look like waves  Longitudinal dunes  Also called seifs- Arabic for sand  Dunes tend to shift in alignment- not a true windward or leeward side  Parallel with each other  One side is not steeper than the other  Star dunes  Form where winds are always shifting  Shaped like stars  Each side kind of looks like a barchan dune



Reg



o Also called desert pavement o All the sand has been blown away, so rocks leftover create a sort of pavement Basin and Range o Water in basins does not flow out to the oceans o Playas: dry lake beds





o Alluvial fans: arid landscape equivalent of a delta Mesa and Scarp o Plateaus  Plateaus are capped with a hard rock layer that is fairly resistant to water erosion o Pinnacle – butte – mesa – plateau o Scarps are the cliffs on these features Badlands o Elevated terrain made up of soil and rock that isn’t consolidated very well- erodes very quickly o Plants can’t grow well...