Module 4

Question 1

Geomorphology

Answer 1

The study of “the lay of the land”; Asks broad questions about the surface of the earth
Why are there mountains?
Why are valleys straight?
Why do cliffs go up to shore?
Why are hills craggy or rounded?

Question 2

Landforms; basic definition, list them

Answer 2

Mountains (tall and craggy, low, isolated/chains)
Valleys (steep/gentle, wide/narrow, straight/curved, isolated/connected, V or U shaped)
Streams (Large/small, long/short, connected, bedrock/alluvial stream, deltas/estuaries)
Deserts (rocky/sandy, flat/sloping, dry/wet)
Glaciers (valleys/sheets, growing/receding)
Coasts (Emergent/Submergent, primary(tectonic origin)/secondary (marine origin))
Karst Landscapes (bedrock dissolved by water, IE limestone. Sinkholes develop, becomes conduits for water to reach surface)
Lakes
Crystalline Rocks
Folded sed rocks, slopes, faults, volcanoes

Question 3

Landform maturity, explain it!

Answer 3

Maturity develops as a formed landform gets more eroded, typically fluvial erosion. Youthful landforms have undeveloped water drainage patterns (V shaped stream that are beginning to cut through bedrock), high relief/tall or steep)
Matured landforms: More U shaped profile, “subdued” or shallow topography, mature tributaries and water pattern. Erosion and deposition balance out (equilibrium).

Question 4

Morphologic vs Genetic classification

Answer 4

Morphologic is more general, genetic more specific
Morph ex: Glacial features
Genetic Ex: Ground moraine, Kettle lakes (glacier leaves behind buried ice that melts and forms a pocket of water)

Question 5

Watershed

Answer 5

A region where all preticipation eventually flows into and through a common point. Watersheds bound with each other and do not overlap.

The Uppermost region of the watershed has high water energy that erodes into bedrock, carrying large sediment down the slope. As this water exits the mountains, it drops the largest sediment and enters the Lowermost portion.
The Lowermost region (alluvial portion): Here streams meander through widened valleys. It is underlain by alluvium, whose sediment is fueled by the river. Alluvium can be thousands of feet deep. Discharge is high and river is wide. Laminar flow (water moves in sheets, unperturbed) means velocity is high.

Question 6

Laminar and Turbulent Flow

Answer 6

Laminar flow means water moves smoothly in sheets distinguished by velocity. Water moves slower closer to the bed.
Turbulent flow is more chaotic, and is produced when there are obstacles

Question 7

Fluvial geomorphology

Answer 7

Bank-the sides
point bar-inner side of a meander, finer sediment, shallow slopes and slow velocity
meander- curve in a meandering river
Paleochannel: buried evidence of ancient river path
Flood Plains-flat earth flanking a river where water floods.

Question 8

How to tell elevation from a picture of a watershed

Answer 8

Water will always flow down from many locations through tributaries into ONE CENTRAL TRUNK. The central trunk is the lowest.

Question 9

What is a river’s base level

Answer 9

Defined by local water body’s such as sea level, lakes, major rivers, reservoirs. River’s will progressively erode down to base level over time, if given enough.

Question 10

Where should a reservoir be placed relative to a stream

Answer 10

Uppermost portion, especially upstream of a knick point (massive steepening of topography) Water can be distributed from there using gravity to lower area, or dropped through turbines for electricity.

Question 11

Where are agriculture and urban centers relative to a stream

Answer 11

Lowermost portion. The thick alluvium serves as an aquifer for the water, to be used by society.

Question 12

Glacier landforms; list them!

Answer 12

High Mountain group
Arretes: Knifepoint ridges that flank and were carved out by glaciers that dug through.
Paternoster Lakes-The playa lake of glaciers. Glaciers form bowl shaped depressions as they carve through. These are later filled with water. Can There are usually multiple Paternoster Lakes that for a straight or necklace shape patterns.
Plains Group
Drumlin fields- group of teardrop shaped hills that taper toward the direction of glacier movement.
roche moutonnée-shaped like ripple marks, steep side indicates direction of glacial movement. “Stoss” or upice side.

Question 13

Stoss

Answer 13

Side of a landform ice moved toward, indicates direction of movement

Question 14

Glacial Landforms-What to look for as an engineering geologist

Answer 14

Over-consolidated clays: Squashed by thousands of feet of ice, these clays are stable ground for building.
Boulder clays-Core’s may show boulder shallow under the surface, but since its a till it doesn’t mean the bedrock will immediately underlie it.
Hydrocollapsible loess- collapses under water, poses danger to structure. Loess is loosely held together and can have high relief.
Gravel Eskers-good source of gravel for use in concrete.
Kame Terrace-Terrace or step-like form that typically is found between periglacial and subglacial environment.

Question 15

% of precipitation in a watershed that can be available later

Answer 15

30%

Question 16

What is an active fault. Why did geologists settle on this value?

Answer 16

has ruptured in the last 11,700 years. This is because the weather became more arid 11,700 years ago. If a fault cross cuts a lacustrine deposit, it has moved since 11,700 years ago. If the deposit is consistent across, then it hasn’t moved and is inactive.

Question 17

Geomorphic evidence for holocene (active) STRIKESLIP faulting, and why

Answer 17

Sag ponds-absence of lacustrine deposits within the sag pond
scarps showing little erosion-elevation differential that hasnt been weathered down yet
offset stream courses-a stream can be visibly mature or juvenile
Offset Drainage channel
Shutter ridge-drainage path has been diverted to one side due to strike slip movement
triangular faceted spurs-a sort of triangular scarp that forms if the front of a ridge gets pulled down by a normal fault.

Question 18

Geomorphic evidence for holocene (active) REVERSE faulting, and why

Answer 18

Rollover folds
topple blocks

Question 19

Recognizing Late Quat, Quat, and PreQuat faults

Answer 19

Late-same as holocene, but less distinct
Quat-displaces plio-pleistocene aged rock within last 1.6 ma
PreQuat-older than 1.6 ma, no evidence of displacement

Question 20

Capable Fault

Answer 20

Capable fault is a fault that is deemed capable of generating levels of seismic activity (shaking) that is relevant to the structural integrity of things like power plants. It must also be considered likely to produce seismic given the larger tectonic context. If there is continental extension, normal faults will be considered capable and reverse faults won’t.

Question 21

Plan “Satellite” view features to look for when finding land slide deposits

Answer 21

Concave bending of contour lines- it wasn’t concave before, but that part of the hill fell.
Hanging ponds-shows a landslide happened recently, lakes down form on cliffs.
Hummocky (bumpy) ground)
Springs (precipitation quickly travels out of the loose landslide deposit down into the valley)

Question 22

Sediment cohesion

Answer 22

The internal molecular attraction between sediment molecules that hold structure together. Serves as a resistant force against landslides.

Question 23

Factor of Safety of a slope (that might landslide)

Answer 23

resistive forces vs driving forces
Stable=>1, stable>driving
Unstable=<1, stable<driving

Question 24

Landslide features

Answer 24

-Box or 90 degree canyon that marks the crown or top of the landslide slope.
-Terraces (steps) with ponds
-Hummocky ground
-Vegetation past the hummocky ground (precipitation travelling through the ground)

Question 25

Multispectral satellite images

Answer 25

Bands or lenses each “see” different wavelegnths of light, including blue green and infrared. infrared lens is used to see where vegetation is clearly, to see how healthy it is and how fires spread.