Topic 1- Hillside Processes Flashcards
what is active tectonics
ongoing deformation
isostatic uplift
the release of weight from a tectonic plate causing it to rise
- can be glacial or erosional.
what is passive tectonics
indirect influence on process and forms through lithology created by tectonics
describe weathering as a geomphic proccess
the disequilibrium response of rock bodies because they are under different temperature and pressure stresses than when they where formed.
how does climate effect landscapes? three types of geomorphology
glacial, coastal, fluvial geomorphology
why is sand everywhere
its quartz, and its hard to break down
what are the two types of hillslopes
transport-limited, and weathering limited hill slopes
what is the general shape of a hillslope
convex, straight, concave.
weathering, transport, and depositional dominated.
like a cos wave
what are the two forces acting on a slope
driving and resisting
Driving & resisting forces are components of what
Fg, The force of gravity
what is the equation for Fg
Fg=mg
what is the difference between shear strength and resisting forces?
haha tricked you, they are the same!
how is Shear strength (S) calculated
Mohr-Coulomb equation:
S = (effective normal stress)Tan (angle of internal friction) + Cohesion
define stress
force per area
define density
mass per volume
what is Normal stress
the stress oriented perpendicular to the slope.
what is one way to reduce Normal stress
by any amount of pore water pressure
what is pore water pressure
an additional variable that impacts the effective normal stress and is dictated by the height of the water table
what is the angle of internal friction
the mechanical resistance to sliding , friction
what is the issue with angle of internal friction
it cannot be directly measured
what effects the angle of internal friction
grain roundness, grain size, packing , uniformity of grain size
how is internal friction quantified
through the angle of internal friction, which is the angle a sediment can hold before failure`
what is cohesion
a resisting force that is caused by chemical bonding, and electrostatic attraction.
what is cohesion as a variable
alwasy positive
what sediments have zero cohesion
all do, only an ideal perfect sand would have zero cohesion
what are driving forces
shear stress that is oriented parallel to the slope
what is the factor is safety Fs
the ratio between resisting forces and driving forces. AKA shear strength over shear stress.
if Fs is 1, >1, <1 what does it mean
balanced, stable, unstable
what are the two Types of triggers
External (increase shear stress), and Internal (decrease shear strength) factors
what is Rheology
the study of flow and deformation of material under applied forces
what are the three types of stresses
tensile(pulling), compressive(crushing), shearing (sliding)
what are the three types of rheological responses.
elastic, plastic, and viscous fluid
define elastic deformation
returns to the orginal shape after stress is applied
define Plastic deformation
does not go back to the original shape after stress is removed
define Brittle failure
loss of cohesion, usually occurs at the earths surface
define viscosity
internal resistance, that remains constant in newtonian fluids
Define Dilatant and Pseudoplastic
shear thickening, vs shear thinning
what is liquefaction
loss of soil strength under shocl and leads to fluid behaviour
what is Creep
the upward heave with downslope displacement, periodic soul expansion and contraction.
mass wasting classification triangle. what are at the three corners
flow, heave, slide.
what does the cross section of a slide look like
equal movement at the surface and on the sliding plane
what does the cross section of a pure flow look like.
surface flow is faster than bed flow.
what does a pure heave cross section look like
Expansion up and Contraction down.
what is Debuttressing
cracking occurring in the side of U-shaped valley due to the release of glacial pressure
what is a subaqueous landslide
a slide that starts underwater
what is a subaerial landslide
A slide that starts above water
how do wildfires affect permiability?
reduces, forms water repellant layer
