Geomorphology Exam 1

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Geology

75 Terms

1

geomorphology

the study of the processes shaping the Earth’s surface and the landforms and deposits that they produce

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2

Nicolaus Steno (Niels Stenson)

1638-1686, developed self-named “laws”: the law of superposition and the law of original horizontality. worked within a biblical paradigm but is still considered a forerunner in geomorphology.

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3

catastrophists

those who view geomorphology as being shaped by one abrupt and unique event

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4

diluvialists

those that view geomorphology as being primarily shaped by the biblical flood

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5

James Hutton

1726-1797, presented a paper arguing that the Earth’s surface was shaped by slow but continuous processes that are visible today. The work gained more traction with re-release

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6

John Playfair

1748-1819, re-released Hutton’s work after his death

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7

uniformitarianists

those that view geomorphology as being shaped by slow processes

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8

Charles Lyell

1797-1875, known as the father of geology, he developed Hutton’s ideas further

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9

Louis Agassiz

1807-1873, developed a theory that large sediment deposits in Europe and the US were the result of glaciers, not a biblical flood

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10

Relict landforms

those shaped by processes in the past that are not at work today

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11

T.C. Chamberlin

1843-1926, developed the concept of multiple working hypotheses and named the glacial sequence present in North America

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12

John Wesley Powell

1834-1902, introduced base level as the elevation below which a stream cannot downcut

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13

local base level

the lowest topographic level in a region which all the surrounding stream systems are graded to

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14

G.K. Gilbert

1843-1918, focused on inductive reasoning and multiple working hypotheses. He was the first to suggest tectonics, the first to use flume experiments, and he developed the concept of equilibrium

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15

William Morris Davis

1850-1934, very qualitative approach to geomorphology, assumed we understood the processes at work, interested in geographic cycles

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16

peneplain

beveled off surface at the start and end of a geographic cycle according to William Morris Davis

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J. Harlen Bretz

1882-1981, suggested a catastrophic flood in eastern Washington, and was kind of right

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18

process geomorphology

quantitative analyses to relate geomorphic processes to land forms

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19

Luna Leopold

1915-2006, focused on explaining the physics underlying fluvial processes

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20

Ralph A. Bagnold

1896-1990, related physics to eolian processes

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21

Stanley Schumm

researched the relationship between precipitation and erosion, realizing that vegetation is the critical factor

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22

how do we know about paleo-precipitation in Jordan?

soil samples indicate paleo-wetlands (soil calcium carbonate), unconformities (indicate water table drops), and paleo-mud deposits indicate flooding

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23

isostasy

the movement of Earth’s surface up or down due to loading (ice or water) or erosion. explains the differences in relative height between continents and oceans.

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24

isostatic compensation

idea that for every one meter of rock eroded, 80 centimeters of uplift will occur

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25

endogenic processes

tectonics and volcanism, drive orogenies and determine first-order topography

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26

exogenic processes

primarily erosional, driven by the Sun’s energy and the temperature gradient between the poles and the equator

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27

how do lithology and structure influence topography?

different rock types vary in their resistance to weathering, the type of soils they produce, and the durability of weathered material. the degree to which rocks hav been tectonically fractured, sheared, or deformed influences material strength.

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28

what effects do plants have on topography?

they can hold soil in place, influence distribution of permafrost, and impact impact infiltration and overland flows

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29

how do animals impact topography?

they can do so through overgrazing burrowing, and soil compaction, amongst other influences.

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30

landscape evolution

matching types of measurements and the understanding of geomorphic processes to the spatial and temporal scales over which relevant processes act

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31

how old are most landscapes? how long does it take them to form?

depositional landforms are not typically more than 1 million years old. it typically takes millions to 10s of millions of years to form a landscape

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32

what relationship lies at the heart of geomorphology?

process and form

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33

equilibrium

a delicate balance between landforms and processes

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34

thresholds

the limits of equilibrium. when they are exceeded, the system is in disequilibrium and a major response may occur (landslide, deep stream incision)

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35

extrinsic threshold

when a system is pushed to limiting conditions by variations in external controlling factors (climate, tectonics)

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36

intrinsic threshold

when instability and failure of a system occur even though external variables remain relatively constant

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37

applications of geomorphology

  • feeding a growing population sustainably

  • ecological restoration

  • planetary exploration

  • natural hazard assessment, prevention, and recovery

  • foundation of rational land-use planning and landscape management

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38

geomorphic cycle

a sequence of geological and geomorphic processes that shape and reshape the Earth’s surface over a long period of time; one is driven by natural forces such as tectonic plate movement or weathering

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39

catastrophic event

a sudden and significant geological event that results in widespread and severe changes to the Earth’s surface

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40

active remote sensing

involves instruments sending out a pulse of energy, receiving it back, and analyzing the characteristics of the energy pulse; ex: radar

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41

what is InSAR and what types of events is it used for?

this is a type of radar and best used to measure changes associated with events (earthquakes, floods, small eruptions) or gradual changes over decades (groundwater subsidence, significant erosion)

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42

what is LiDAR and when is it best used?

this is a type of radar and is best for US usage

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43

digital elevation models

maps where points on the landscape have been assigned values for their horizontal and vertical positions, created with LiDAR and SRTM data

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44

relative elevation models

used when elevation in regards to other area topography is more important than actual elevation (floodplain surfaces and alluvial fans)

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45

passive remote sensing

essentially photography; uses detectors to measure the amount and wavelengths of energy emitted from the surface of the Earth such as satellite imagery

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46

what types of field tests occur in geomorphology?

sprinkling test for slope failure, grain-size analysis for sorting, marked clasts for movement

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47

what types of lab experiments occur in geomorphology?

physical model manipulation, flume experiments, rock weathering

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48

how do soils change over time?

they become redder and finer textured. carbonate decreases in arid areas and clay increases

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49

how do alluvial fans change over time?

they become darker and redder

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50

paleomagnetic dating

uses reversal records for fine drain deposits older than 780,000 years old. useful in stream overland deposits and lake deposits

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51

amino acid racemization

useful for anything that has proteins, such as shells, wood, or bones, with an age range of 100-100,000 years old

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52

core stone

bedrock that has been weathered in place

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53

how old is a landscape?

not typically over 1 million years old

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54

how long does it take a landscape to form?

millions to 10s of millions of years

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55

luminescence dating

works for sediments that were exposed and buried that consist of a homogenous unit with no significant weathering or water saturation, useful for wild transported sediments especially, good for things 100-200 thousand years old

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56

horton overland flow

occurs primarily in arid areas, due to lack of permeability in a soil

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57

saturation overland flow

occurs in humid areas due to pore spaces being filled

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58

what factors control infiltration?

  • grain size

  • permeability

  • vegetation

  • compaction

  • burrowing

  • slope

  • intensity and duration

  • saturation

  • climate/seasonality

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59

what controls groundwater flow?

permeability and porosity

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60

carbon-14 dating

best used on wood and coal aged around 45,000 years old

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61

K/Ar dating

used for volcanic deposits including pyroclastic flows that are between 100,000 and 10.4 billion years old

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62

cosmogenic nuclides

capable of dating very old materials like minerals or whole rocks, can be used to determine erosion rates as well as the age of a landform; applicable to the entire quaternary period

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63

cesium-137 dating

based on isotope produced by nuclear bomb testing, good for recent deposition and erosion as well as understanding sources of sediment

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64

recurrence interval

the likelihood of an event, eg a 100 year flood has a 1% chance of occurring in any given year, a 50 year flood a 2% chance, etc

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65

groundwater sapping

seepage undermines slopes and drives mass wasting

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66

seepage erosion

occurs along contact between permeable and impermeable units, creates groundwater sapping

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67

features of groundwater sapping valleys

  • amphitheater-shaped heads

  • steep canyon headwall

  • spring discharging at canyon head

  • stubby drainage pattern

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68

allogenic valleys

ones that head in insoluble rocks adjacent to karstic area and then flow into karstic region and become deeply incised

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69

blind valleys

ones that terminate at a cliff face

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70

pocket valleys

begin where groundwater resurges, opposite of a blind one

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71

dry valleys

one that has no water

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72

planetary geomorphology

use of Earth analogs to classify landforms, infer surgical processes, and gain understanding of past environmental conditions on other planetary bodies

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73

what surface processes do we believe took place on Mars?

  • weathering

  • soil development

  • mass wasting

  • fluvial processes

  • groundwater processes

  • eolian processes

  • glacial processes

  • periglacial processes

  • coastal processes

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74

what created the moon’s topography?

  • mass wasting

  • weathering

  • impacts

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75

what are the main differences in boundary conditions affecting geomorphic processes on other planetary bodies?

  • plate tectonics

  • volcanism

  • hydrological processes

  • distance from the sun

  • meteor bombardment

  • atmosphere presence

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