Principles of geomorphology

Question 1

What does the Hjulstrom curve describe?

Answer 1

Erosion thresholds based on particle type and velocity (force and resistance)

Question 1

What does the Hjulstrom curve describe?

Answer 1

Erosion thresholds based on particle type and velocity (force and resistance)

Question 2

What are the 5 key principles of geomorphology?

Answer 2

EFTFT
1. Equilibrium
2. Force (and resistance)
3. Thresholds
4. Feedback
5. Time

Question 3

Describe uniformitarianism

Answer 3

Geo formation processes are slow and steady over time – this helps us understand the history & nature of landforms

Question 4

Describe catastrophism

Answer 4

Some things happen very quickly and dramatically, disrupting uniform patterns in landform evolutions

Question 5

Describe the general geographic cycle

Answer 5

young -> mature -> old -> young

Question 6

Give an example of an endogenic process?

Answer 6

Plate tectonics, landform evolution

Question 7

Give an example of an exogenic process

Answer 7

Weathering, erosion, transport, deposition

Question 8

What is a morphological system?

Answer 8

A system where the morphology is influenced by forces acting upon it

forces affect morphology - morphology affects further morphology

Question 9

What is a cascading system?

Answer 9

The output from one system becomes the input for another. Dynamic system characterized by transfers in mass and energy

Question 10

What is a process-response system?

Answer 10

system that integrates characteristics of morphological and cascading systems

Question 11

What are the 4 types of equilibria?

Answer 11

-Static
-steady-state
-dynamic
-Dynamic-metastable

Question 12

Energy: What are the key sources of energy in the geomorphological systems?

Answer 12

-Solar system: rotational energy
-Solar radiation
-Gravitational attraction
-Plate movement
-Geothermal heat flow

Question 13

What are the 5 contributing factors of landscape evolution?

Answer 13

-Climate
-Tectonics
-Topography
-Geology
-Biology

Question 14

How does an igneous rock form?

Answer 14

Directly from the cooling, solidification & crystallization of magma

ex. basalt, granite

Question 15

How does a sedimentary rock form?

Answer 15

From the compaction and cementation (lithification) of erodied and deposited sediments.

Key processes: weathering, erosion, transportation, deposition.

ex: sandstone, limestone, shale.

Question 16

How are metamorphic rocks formed?

Answer 16

When any igneous or sedimentary rock undergoes physical or chemical changes under pressure & increased temperature. They are usually buried.

The metamorphic changes in mineral type always reflect the restoration of equilirbium

ex: slate, gneiss, marble

Question 17

What are the parts of the earth’s structure (spheres)

Answer 17

Lithosphere - outer
Asthenosphere - middle
Mesosphere - inner

Question 18

Describe the continental crust:
-general composition
-avg density
-avg depth
-upper composition
-lower composition

Answer 18

-General composition: SiAl (silica & aluminum)
-Avg density: 2.7g/cm3
-Avg depth: 30-40km
-Upper composition: granite rocks
-Lower composition: basalt and diorite

Question 19

Describe the oceanic crust:
-general composition
-avg density
-avg depth
-general composition

Answer 19

-General composition: SiMa (silica & magnesium)
-Avg density: 3.0g/cm3
-Avg depth: 6-11km
-Composition: Tholeiitic basalt

Question 20

What are the 3 sources of knowledge to understand earth’s inner structure?

Answer 20

Volcanoes
Gravity measurements, magnetism
Seismology - earthquakes

Question 21

What did the geophysicist Inge Lehmann discover?

Answer 21

The existence of the inner core via extra vibrations coming from what must have been the inner core

Question 22

What is isostasy?

Answer 22

adjustment of the earth’s crust in response to something weighing on the lithosphere.

Question 23

Continental drift: when did Pangea, the supercontinent, exist?

Answer 23

200-250 mya

Question 24

What lines of evidence are there for Pangea?

Answer 24

-Fossil similarities across several regions (particularly Gondwanaland) -Patterns of glacial erosion, deposits & geology

Question 25

What 4 scientific developments spurred the plate-tectonics theory?

Answer 25

-Demonstration of ruggedness and youth of the ocean floor -confirmation of repeated reversals of the Earth magnetic field in the geologic past -Emergence of the seafloor-spreading hypothesis + associated recycling of the oceanic crust -Precise documentation that the world's earthquake & volcanic activity is concentrated along oceanic trenches & submarine mountain ranges

Question 26

Seafloor spreading

Question 27

What are the 3 types of results of crustal movement / uplift?

Answer 27

-tectonic mountains -volcanic landforms -residual mountains (remnants of ancient tectonic activity)

Question 28

What are the 3 types of plate boundaries?

Answer 28

-Divergent -Convergent -Transform fault (sliding past each other)

Question 29

What are the 3 types of convergent boundaries?

Answer 29

-subduction -convergent -transform fault margins

Question 30

What is epeirogeny?

Answer 30

change in the global disposition of land masses (e.g. continent formation)

Question 31

What is orogenesis?

Answer 31

Process of mountain formation driven by plate tectonic movements.

Question 32

What is diastrophism?

Answer 32

The combination of epeirogeny and orogenesis - folding or faulting

Question 33

What are the 2 forms that a diastrophic fold can take ?

Answer 33

Anticline & Syncline

Question 34

What are the 3 types of plate boundaries?

Answer 34

Divergent Convergent Transform Fault (sliding past each other)

Question 35

What type of movement is the seafloor spreading cycle?

Answer 35

Convectional

Question 36

What causes seafloor magnetic stripes?

Answer 36

volcanic flows that cool during different orientations of earth's magnetic pole

Question 37

What is regolith?

Answer 37

an unconsolidated surface layer of weathered rocks

Question 38

Why do rocks weather?

Answer 38

rocks exposed at the surface by erosion are no longer in equilibrium with their environment

Question 39

What are the 4 types of physical weathering?

Answer 39

-Freeze/thaw (frost action) -Exfoliation (expansion/contraction) -Abrasion -Root wedging

Question 40

How does chemical weathering affect physical weathering?

Answer 40

Chem. weathering creates more stable, but more breakable, chemical compositions. They become physically weaker.

Question 41

How does physical weathering affect chemical weathering?

Answer 41

Physical weathering increases the surface area for chemical weathering to take place.