Question 1
A geologist is looking at deposits along a river below a large volcano. She finds large boulders mixed with sand and mud, and all of the material is comprised of volcanic rocks, particularly the mud which is volcanic ash. She quickly realizes these deposits represent an ancient ________.
◦ earthflow
◦ slump
◦ rock avalanche
◦ lahar
Question 2
In deserts of southwestern North America developers often build houses in dry stream beds and build only minimal subsurface drainage systems to handle a flow of water comparable to the size of the dry stream channel. Is this a reasonable development model in the interest of public safety?
◦ No, giant rock avalanches could come down the valley covering houses.
◦ Yes, any potential flooding catastrophe would be a 100 year flood event and would have adequate warning to evacuate people for safety, so the drainage system is adequate.
◦ Yes, although flash floods can occur, using the channel size is a reasonable estimate of the maximum flood size.
◦ No, flash floods can produce high viscosity mudflows that would not be captured by the drainage system and could flow out over the valley, destroying everything in its path.
Deserts differ across the world. (a) Acacia trees between a gravel plain and sand dunes in the Namib
Georges Braque, Houses at l'Estaque.
Influences on Temperature: South-facing slopes are typically more vegetated than north-facing ...
The Dust Bowl in North America
Deserts on the world map
North American temperate deciduous forest. Forest soil profile at right.