Final Exam Flashcards

1
Q

controlling force of mass wasting

A

gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

the important factors in mass wasting

A

earth material, water content, slope
• Consolidated material (tightly arranged sediment) will not waste as easily s unconsolidated (loosely arranged sediment)

• Oversaturation of water content will lubricate the sediment and cause the sediment to be very loosely attached
Saturation will cement the sediment together and cause it to be tightly attached
No saturation will cause the sediment to be loosely attached.
Think of this with sand and building a sand castle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

types and rates of movement

A
  • Creep – very slow
  • Slump – relatively slow
  • Avalanche – very brief and extremely rapid
  • Mud Flow – ~100mph, very rapid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Creep

A

very slow wasting, it is the downward progression of rock/soil down a gradient caused by gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Slump

A

form of mass wasting that looks like stair steps on a hill. Caused by movement of loose sediment by earthquakes shocks, wetting, and freezing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Avalanche

A

sudden and drastic flow of snow down a slope caused by loading of new snow (causing too much weight) or an earthquake.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mud Flow

A

very rapid movement of loose soil and water down a gradient, caused by over saturation of sediment, flooding, and eruptions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Rock Slides

A

can happen due to erosion of the base of a cliff over time eventually causing the top part of the cliff to topple due to its unstable nature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Debris flow and debris avalanche

A

Debris flow and debris avalanche are similar to mudflow / avalanche just with different sediment. Rockfalls and debris falls form a pile of debris that pile up to form a talus under a cliff

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

effects of deforestation on mass wasting

A

• Deforistation causes the sediment to be less consolidated (causing the sediment to become loose) which can increase the risk of mass wasting events.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

difference in stability for rock layers – beds parallel a valley slope and those beds which dip into the valley wall.

A
  • Beds that are parallel to a valley slope become a potential slip surface which can cause mass wasting, especially when water saturates the area between the valley’s sedimentary rock layer and the bedrock.
  • Beds that dip into the valley wall will not slip along the bedrock.

• Think about the surface of wood with the grain and then against the grain, with the grain it’s much more slick (bed parallel to a valley slope), against the grain it’s not slippery (bed dips into a valley wall).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the triggers for mass wasting? Can human activity trigger mass wasting? How?

A
  • Triggers of mass wasting include; earthquakes, flooding/wetting, freezing of water in sediment, animal activity, etc.
  • Humans can trigger mass wasting in many different ways including; removal of vegetation, increasing angles of slopes, addition/removal of water, etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

➢ How do rivers and streams fit into the hydrologic cycle (run off verses infiltration)? What are the different water reservoirs? Be able to place them in order from largest to smallest.

A
  • Rivers and streams fit into the hydrologic cycle (the water cycle) because they transport water. Infiltration is where water on the ground surface enters the soil, run-off is when the soil is saturated to full capacity due to infiltration and any additional water flows over land (creating rivers and streams). Run-offs are the primary agent in all water erosion.
  • Rivers and streams transport their run-off water to water reservoirs such as lakes and oceans. Oceans obviously the largest.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How are materials transported in rivers and streams?

A

Through the force of the water’s current. The higher the velocity of a current the larger the sediment a stream/river can transport.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are stream divides and drainage basins?

A

A drainage basin is the extent of an area where all the run-off water converges to a single point (such as a single river, lake, ocean, etc).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Be able to recognize the difference between stream channel types

A

straight, meandering, braided
• Also remember that braided streams can move the most sediment / water the quickest (he’s stressed this in lecture). The point bar is deposited sediment on a meandering stream (the sediment deposits because the stream’s current slows down around the sides). The cut bank is eroded land from water erosion. (you will need to know cut bank and point bar).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

the different stream drainage patterns and what each tells you about the underlying rocks

A
  • Meandering channel forms on low slopes through easily eroded bedrock.
  • Dendritic has flat lying layers / bedrock
  • Trellis has folded rock layers.
  • Rectangular drainage has joints and faults
  • Radial drainage occurs on high mountain peaks or volcanoes.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

➢ Describe how velocity changes within a meandering stream. How does this lead to the formation of point bars and cut banks? How do meandering streams change over time?

A
  • Velocity is fastest in the middle of meandering streams and slows down around the edges. Point bars are formed on the edges of streams where the velocity of water slows down enough to where sediment can be deposited, cut banks form from the erosion of the land from the water.
  • Meandering streams change from (youthful) → (mature) → (old age) over time.
  • Youthful streams have a narrow channel width.
  • Mature streams have a wide channel length (due to erosion).
  • Old age streams have an even wider channel length and are represented by oxbow lakes which are essentially scars in the sediment where the meandering stream use to run.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Velocity of a stream

A

• Velocity of a stream / river is how fast the water is moving.

20
Q

Gradient of a stream

A

essentially the steepness (higher the gradient higher the slope).

21
Q

Discharge of a stream

A

generally written in cubic feet / second, it is the amount of water / sediment that flows from a stream / river every second.

22
Q

Floodplain

A

• Floodplains are broad flat areas bordering a stream / river, this is an area which has been flooded by that river / stream before.

23
Q

Levees

A

• Levees are naturally formed from rivers / streams. This is where sediment is piled up along the ridges of rivers.

24
Q

Terraces

A

• Terraces are formed by erosion from rivers, they appear as stair steps along the ridges of rivers.

25
Q

Alluvial fans

A

• Alluvial fans are ‘fan shaped’ deposits of sediment that are formed from fast flowing rivers that slow down (near the end of the river) and spread out.

26
Q

Deltas

A

• Deltas are formed at the mouth of a river where it flows into an ocean or some type of reservoir.

27
Q

If a flood has a recurrence interval of 20 years, what is the % chance that this magnitude flood will happen this year? What about the next year? (This applies to 5, 10 or any flood event)

A

• Probability of a flood occurring can be determined by the equation of
Annual Probability = (1 ÷ recurrence interval)
• In this particular example the chance it will happen this year or any year is 1/20. Rivers that have gone a long time without flooding will be the largest.

28
Q

describe the hydrologic cycle.

A

• In the water cycle, some water is transported to reservoirs via streams / rivers, some water is evaporated into the atmosphere, and some gets trapped into glaciers. The remaining water sinks into the soil and ground through infiltration.

29
Q

List the factors that control the rate of groundwater recharge (infiltration).

A

• The higher the porosity of a ground rock the more water it can hold (faster ground water recharge), the higher the permeability of a ground rock the easier it is to infiltrate with water.

30
Q

Unsaturated Zone

A

• Unsaturated Zone – a zone that has empty pore space between the rock (more water can enter).

31
Q

Saturated zone

A

• Saturated Zone – a zone that does not have any empty pore space between the rock (saturated with water already)

32
Q

Water table

A

the water level in a certain area

33
Q

Porosity

A

amount of ‘empty space’ (pore space) between sediment. Remember that small sorted sediment actually has more pore space than large sediment. This is why sand can hold water so much better than pebbles.

34
Q

Permeability

A

waters ability to go through a rock

35
Q

Aquifer

A

a layer of rock that contains permeable rock (water can easily move within an aquifer).

36
Q

confined aquifer

A

a layer of rock that contains permeable rock surrounded by non-permeable rock (such as clay) which keeps the water inside the confined aquifer.

37
Q

Artesian Well

A

a naturally occurring well that spurts up water due to the fact that it is below the water table. Artesian wells will be active until the water level reaches the well’s level or goes below it.

38
Q

Cone of depression

A

occurs when water is being sucked out from a water table (such as from a well). A cone of depression will occur around where that water is being extracted from.

39
Q

Subsidence

A

• Subsidence is where ground level will decrease relative to sea-level (or the water table) in a certain area.

40
Q

Salt water intrusion

A

• Salt-water intrusion can occur along the coast near bodies of salt water, It is caused by ground-water pumping from coastal wells and occurs when the water-table of that well reaches the salt water’s water table. Wells that have salt-water intrusion are generally discarded as they cannot be fixed easily.

41
Q

What is the difference between hot springs and geysers? What heats the water of hydrothermal activity? What is the source (plate boundary or hot spot) of heat for the geysers of Yellowstone?

A
  • Hot Springs occur where very deep groundwater is heated from warm bedrock and then rises (heat rises) spurting out of a hot spring. Hot springs form in places with faults and high permeability.
  • Geysers are similar however they occur due to a large body of ground water that is heated by bedrock producing steam which rises and causes immense pressure to water near the surface forcing it out of the geyser’s vent.
  • Hot/Molten bedrock heats the water of hydrothermal activity, the source of heat for the geysers of Yellowstone is the Yellowstone Hotspot, an underground volcanic system.
42
Q

Karst

A
  • Karsts are geological formations shaped by dissolution of layers of bedrock.
  • Karst formations are related to groundwater because water causes dissolution of bedrock, and groundwater can slowly carve out underground areas of bedrock (caves) through dissolution.
43
Q

Dissolution

A
  • Dissolution is the chemical weathering of rock where water dissolves the rock away over time
  • Dissolution forms caves because water can erode enough bedrock over time where gaping underground holes (caves) are created.
44
Q

Speleothems

A

• Speleothems (aka cave formations) are mineral deposits in caves. They are formed in limestone.

  • Stalactites form on the ceiling of a cave and branch down (c-tites, ceiling tight)
  • Stalagmites form on the ground of a cave and branch upwards (g-mites, ground mighty)
45
Q

What are some possible sources for groundwater pollution that you may see in a rural or urban setting?

A

• Possible ground pollution is from septic tanks (this is why people always put septic tanks below their well’s in urban areas) and from large farms (animal feces).