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Earth Systems > Intro to Geomorphology > Flashcards

Intro to Geomorphology Flashcards

1
Q

What is Geomorphology?

A
  • The study of the physical features of the surface of the earth and their relation to its geological structures.
  • Understanding and explaining how landscapes like this form
  • The science of landforms and the processes which form them. E.g. weathering, erosion, transport and deposition
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2
Q

What are one of the applications of geomorphology currently?

A
  • Decisions about how to manage the Reef (Great Barrier Reef) Water Quality rely heavily on the use of sediment budget models – which are Geomorphic models
  • Geomorphologists have identified landscape features such as gullies as the primary sediment source to the GBR!
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3
Q

What is Fluvial Geomorphology?

A
  • The study of the interactions between the physical shapes of rivers, their water (function of the river) and sediment transport processes, and the landforms they create.
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4
Q

Study the diagram of Geomorphology in the rock cycle.

A

https://docs.google.com/document/d/11SlS_6djE3BGAezT2-FeVRTdxG1P1jVyj-u3X2L5qDo/edit?usp=sharing

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5
Q

What processes are the main contributors to geomorphology?

A
  • The Earth’s surface is shaped by the constant interaction of two sets of processes: Endogenic and Exogenic. The interaction of the two is complex and occurs in both directions.
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6
Q

What are Endogenic processes?

A
  • Endogenic processes – those originating from the interior of the Earth’s surface;
  • Example: these processes are driven by plate tectonics, e.g. mountain ranges form from convergent plate boundaries
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7
Q

What are Exogenic processes?

A
  • Exogenic processes – those originating from the exterior of the Earth’s surface
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8
Q

What is the difference between Endogenic and Exogenic processes besides where they occur?

A
  • Endogenic processes create topography whereas exogenic processes destroy topography (the arrangement of the natural and artificial physical features of an area.)
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9
Q

What are passive plate landscapes?

A
  • “old” landscape with relatively little active tectonism

- E.g. Australia has an average elevation of 330m whereas Antarctica has 2200m

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10
Q

What are drainage basins and drainage divides?

A
  • A drainage basin is any area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water.
  • The boundary between drainage basins is a drainage divide: all the precipitation on opposite sides of a drainage divide will flow into different drainage basins.
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11
Q

What type of water is found in drainage basins?

A
  • A drainage basin is an area of land drained by a river and its tributaries (river system). It includes water found in the water table and surface run off. There is an imaginary line separating drainage basins called a catchment or watershed
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12
Q

Study the diagrams of the drainage basins and the drainage divide

A

https://docs.google.com/document/d/11SlS_6djE3BGAezT2-FeVRTdxG1P1jVyj-u3X2L5qDo/edit?usp=sharing

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13
Q

What are Interfluves?

A
  • Regions between the valleys of adjacent watercourses, especially in a dissected upland.
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14
Q

What is Sheet flow?

A
  • An overland flow or downslope movement of water taking the form of a thin, continuous film over relatively smooth soil or rock surfaces and not concentrated into channels larger than rills.
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15
Q

What is a rill?

A
  • A shallow channel cut into soil by the erosive action of flowing water
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16
Q

What are Endorheic basins.

A
  • Also known as internal drainage basins, they are basins where water leaves through evaporation or subsurface gravitational flow because some streams do not reach the ocean.
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17
Q

What is drainage density?

A
  • Drainage density is the total length of all the streams and rivers in a drainage basin divided by the total area of the drainage basin. It is a measure of how well or how poorly a watershed is drained by stream channels
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18
Q

What factors influence drainage density?

A
  • Generally, a humid climate is associated with a high drainage density and a typical desert has a very low drainage density.
  • The drainage pattern is the arrangement of channels in an area, which is influenced by climatic and geologic conditions.
19
Q

What happens to the drainage density if there are different types of soil?

A
  • If the river/stream is underlain by silty clay soil then: there is high runoff potential and high drainage density
  • If the river/stream is underlain by porous material then: there is lower runoff potential and lower drainage density.
20
Q

What are stream orders?

A
  • The stream order is a positive whole number used to indicate the level of branching in a river system
21
Q

How do stream orders work?

A
  • 1st order stream segments are the smallest un-branched segments that divide from 2nd order branches
  • 2nd order segments are those formed by dividing third order branches
  • 3rd order segments are formed 4th order branches which attach to the main river
22
Q

Study the diagrams for Stream orders and drainage density.

A

https://docs.google.com/document/d/11SlS_6djE3BGAezT2-FeVRTdxG1P1jVyj-u3X2L5qDo/edit?usp=sharing

23
Q

What are Morphometric laws?

A
  • Morphometric properties of a drainage basin are quantitative attributes of the landscape that are derived from the terrain or elevation surface and drainage network within a drainage basin
24
Q

What type of drainage patterns are there? Which is most common?

A

Out of all the drainage networks, Dendritic are most common

  • Dendritic drainage
  • Trellis drainage
  • Radial drainage
  • Parallel drainage
  • Rectangular drainage
  • Annular drainage
  • Deranged drainage
25
Q

Study the images of the different drainage networks.

A
  • Google doc
26
Q

What is Denudation?

A
  • The exogenic processes that shape the Earth’s landscapes
  • E.g. wearing away of the Earth’s surface by moving water, by ice, by wind and by waves, leading to a reduction in elevation and in relief of landforms and of landscapes.
27
Q

What does Denudation consist of?

A
  • Denudation = Chemical Processes + Physical Processes
28
Q

What is Chemical weathering?

A
  • The erosion or disintegration of rocks, building materials, etc., caused by chemical reactions (chiefly with water and substances dissolved in it) rather than by mechanical processes.
29
Q

What effect does chemical weathering have on different types of minerals?

A
  • Minerals that formed at the highest temperatures and pressures are farthest from equilibrium at surface conditions and therefore are the most susceptible to chemical weathering.
  • Minerals with the simplest mineral structures (e.g., quartz - SiO2, zircon ZrSiO4) are more stable than those with more complicated mineral structures (e.g., feldspars – KAlSi3O8 (K feldspar), NaAlSi3O8 (Albite), CaAl2Si2O8 (Anorthite)
30
Q

What is the main mechanism in chemical weathering?

A
  • Water plays a vital role in nearly all mechanisms of chemical weathering.
  • Water is a highly effective solvent and being a polar molecule it attaches to cations (+) and anions (-) of solids.
  • A proportion of water molecules are always decomposed into H+ ions and OH- (hydroxyl) ions
31
Q

What, second to water, is another main mechanism of chemical weathering?

A
  • Oxygen
  • Free oxygen is rare at crustal depths, but abundant at the Earth’s surface. Certain rocks and minerals will oxidise rapidly when exposed to well-oxygenated soil water, directly to the atmosphere, or to gases in soil pores
32
Q

What is the third type of mechanism that is required for chemical weathering to take place?

A
  • Carbon dioxide

- Rain water will often contain dissolved CO2, that forms carbonic acid

33
Q

In the Morphometric laws, what do the l, s and n represent?

A
  • l = length
  • s = slope
  • n = nutrification
34
Q

What re the two types of chemical weathering?

A
  • Congruent dissolution

- Incongruent dissolution

35
Q

What is Congruent dissolution?

A
  • When a solid dissolves, adding elements to the water according to their proportions in the mineral.
36
Q

What is Incongruent dissolution?

A
  • When some of the released ions recombine to produce new compounds and secondary minerals. For example, not all of the rock will be weathered away and so you get a transformation from one mineral to another
37
Q

What cause disappearing streams?

A
  • The dissolved CO2 in rainwater and cause chemical weathering on limestone and hence create holes in the ground, where the stream flows into. This creates under ground caves and eventually, a spring.
38
Q

Study the diagram of the chemical weathering on limestone.

A
  • Google doc
39
Q

Why are line stone landscapes different to other landscapes?

A
  • Limestone landscapes can undermine drainage basins and drainage divides because they can go underground instead.
40
Q

What are two other chemical processes that are considered chemical weathering?

A
  • Oxidation: (electron exchange). When an ion loses and electron
  • Hydrolysis: (with water) When a free H+ ion or an OH- ion enters the mineral structure to form a new compound.
41
Q

What are the primary agents of chemical weathering?

A
  • Oxygen (O2) and carbon dioxide (CO2) in the presence of water (H2O)
42
Q

Which type of chemical weathering is most common?

A
  • Most reactions are incongruent and so secondary minerals are formed (e.g., clays from feldspars). Some reactions are congruent (e.g., total dissolution of carbonates and the formation of caves)
43
Q

Why is chemical weathering beneficial?

A
  • Chemical weathering makes cations (Ca2+, Mg2+, K+) available to plants
  • Chemical weathering is a process that requires time & is a good pre-treatment agent, followed by physical erosion

Earth Systems (13 decks)

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