EOS 101 Study Guide - Fall 2018, Comprehensive Midterm Notes -
12 Oct 2018
School
Department
Course
Professor
EOS 101
MIDTERM EXAM
STUDY GUIDE
Fall 2018
MASS WASTING
A. What is the difference between mass wasting, erosion, and weathering?
a. Mass wasting = Downslope movement of rock, soil, and sediment due to GRAVITY
b. Erosion = Transport of material by water, wind, or ice
c. Weathering = Loosening or chemical alteration of rocks
B. How deaths annually due to mass wasting?
a. Thousands of deaths per year
C. Mass wasting plays a role in landform development shaping the Earth’s surface.
D. What is the angle of repose?
a. Angle of repose = angle at which unconsolidated material will be stable
b. Affected by grain size, shape, and moisture
i. Steep angle = large grain size, angular grain shape, and moist grains
1. Small amounts of moisture increases cohesion among grains
ii. If grains are saturated, the angle of repose will approach 0
1. Saturation reduces friction and causes sand to flow
E. What are the controls and triggers of mass wasting?
a. Water, such as heavy rainfall, reduces the angle of repose
i. Ex: La Conchita, California
b. Over-steepening of slope (slope is beyond angle of repose)
c. Vegetation removal (via human or fire)
d. Earthquakes (ex: 1964 Turnagain Heights, Alaska)
F. What are the landslide risk factors?
a. Elevation, rainfall, earthquakes, and volcanoes
G. Rate of motion for mass wasting
a. Rapid = Slump, rockfall, rockslide, debris flow (ex: lahar), earthflow
b. Slow = Creep (ex: frost heave), solufluction (ex: regions of permafrost)
H. Distinguish between the types of mass wasting:
a. Slump: rock moves as a unit along a curved surface of rupture
b. Rockslide: detached rock slip along planar surface
c. Rockfall: detached rock fall from irregular surface
d. Debris Flow: water-laden masses of soil and rock rush down mountainsides
i. Confined to canyons, may spread out as alluvial fans at the end of canyon
ii. Lahar: type of debris flow mostly consisting of ash and rock (volcanic
pyroclastic material) and water on volcanoes
e. Earthflow: grains tumble over one another in a viscous fluid (usually due to heavy rain)
f. Creep: gradual downslope movement of soil or regolith
i. Frost heave: type of creep that occurs in places with freeze and thaw cycles
1. Freezing expansion of ice grains move perpendicular to slope
2. Thaw grains drop vertically due to gravity
ii. Trees are curved
find more resources at oneclass.com
find more resources at oneclass.com
g. Solifluction: gradual downslope flow in water-saturated soil during summer in areas
with permafrost
i. Flow of soil and water in upper layer (above the permafrost)
ii. Flows in lobes if vegetation is present (see picture)
I. What happened in the Venezuela (1999) incident?
a. Debris flow after heavy rains, and the town of Caraballeda was built on an alluvial fan
b. 19,000 deaths
J. What happened in the La Conchita, California (1995 and 2005) incidents?
a. Two slumps and earthflows in both years
K. Submarine (underwater) landslides can create tsunamis.
RIVERS (RUNNING WATER)
A. The hydrosphere consists of 97% saltwater and a little less than 3% freshwater. Out of the
3% freshwater, 2.15% is in glaciers and 0.62% is groundwater and 0.03% is surface water
(rivers, lakes).
B. What are drainage basins and their divides?
a. The land area that contributes water to a particular stream or river.
b. The divide separates one basin from another – is at the highest surface elevation.
C. Example of drainage basin hierarchy.
a. Yellow River DB is in Missouri River DB, which is in Mississippi River DB.
D. Evolution of rivers with time (also can be evolution of rivers from headwaters to mouth.
a. The cross-section starts our as a V-shape and becomes wider and wider.
b. Elevated terrain floodplain whole region becomes a low plain
E. What is discharge?
a. Discharge is the volume of water passing a certain point at any given time
i. Varies with time and location
b. Q = (cross-sectional area)(velocity)
c. Q = (channel width)(channel depth)(velocity)
F. The river with the average rate of discharge measured at mouth of river
a. Amazon river, 212,400 cubic meters per second (river with highest average rate of
discharge)
b. Mississippi river, 17,300 cubic meters per second
G. What are the factors affecting water velocity?
a. Gradient (slope of the channel)
i. Greater gradient, greater velocity
b. Channel shape
i. Water velocity greatest at the farthest point from bottom and sides
find more resources at oneclass.com
find more resources at oneclass.com
