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GEOL-1403 > Lesson 13; Running Water > Flashcards

Lesson 13; Running Water Flashcards

1
Q

What is Earth’s water distribution; ocean vs. fresh vs. surface

A

Oceans make up 96.5% of the Earth’s water
Freshwater make up 2.5% of Earth’s water
Surface water makes up 1.3% of the Earth’s water

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2
Q

What term is used by geologists for a running body of water?

A

A stream

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3
Q

Define drainage basin.

A

the area drained by a stream

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4
Q

Define divide.

A

an imaginary line separating one basin from another; sometimes it is visible as a high ridge in a mountainous region, and othertimes it is hard to determine.

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5
Q

What is a continental divide?

A

splitting of a continent into different drainage basins

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6
Q

Define tributary.

A

a smaller stream that flows into a bigger stream

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7
Q

Define confluence.

A

where two streams join/meet

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8
Q

Define source/headwaters.

A

the start of the stream; usually found in mountainous areas

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9
Q

Define mouth.

A

the end of a stream where it enters the sea or a lake.

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10
Q

What is headward erosion?

A

extending the head of the valley upslope; how a stream lengthens its course

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11
Q

What is stream piracy?

A

the diversion of the drainage of one stream into another

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12
Q

What are the different drainage patterns?

A
  1. Dendritic
  2. Rectangular
  3. Trellis
  4. Parallel
  5. Radial
  6. Centripetal
  7. Deranged
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13
Q

How are dendritic drainage patterns characterized? (F1)

A

tree-like pattern; forms over a fairly uniform substrate with a fairly uniform initial slope

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14
Q

How are rectangular patterns characterized? (F2)

A

Streams join each other at right angles. This occurs when a rectangular grid of fractures (vertical joints) breaks up the ground; channels form along the preexisting fractures.

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15
Q

How are trellis drainage patterns characterized? (F3)

A

Develops across a landscape of parallel valleys and ridges; rocks are not homogeneous; streams join the mainstream by eroding soft rocks at a right angle.

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16
Q

How are parallel drainage patterns characterized? (F4)

A

On a uniform slope, several streams with parallel courses develop simultaneously

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17
Q

How are radial drainage patterns characterized? (F5)

A

Drainage networks form on the surface of a cone-shaped volcano outward from the mountain peak

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18
Q

How are centripetal drainage patterns characterized? (F6)

A

Almost identical to a radial drainage system; it flows into a central point

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19
Q

How are deranged drainage patterns characterized? (F7)

A

It occurs in drainage basins where there is no apparent/consistent pattern of streams and lakes usually a region that is geologically disrupted; it is typical of recently glaciated areas.

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20
Q

Compare perennial land ephemeral streams.

A

Perennial streams flow all year long
Ephemeral streams flow for only part of the year

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21
Q

How is stream flow characterized?

A
  1. turbulent
  2. laminar
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22
Q

Characterize turbulent flow.

A

water moving quickly in an erratic fashion horizontally and vertically
individual particles take irregular paths
can keep sediment in suspension longer than laminar flows and aids in the erosion of the stream bottom

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23
Q

Characterized laminar flow.

A

water moving slowly in a nearly straight path
all water molecules travel along similar parallel paths.

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24
Q

What is stream velocity?

A

The distance that water in a stream travels over an interval of time

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25
Q

Where does a stream generate maximum velocity?

A

on the outside curve of a curved channel; this is where erosion occurs

26
Q

Where does a stream generate minimum velocity?

A

on the inside curve of a curved channel; this is where the deposition of sediment occurs

27
Q

What factors affect stream velocity?

A
  1. Slope/gradient of the stream
  2. Channel shape
  3. Channel size
  4. Channel roughness
  5. Discharge
28
Q

How does flow velocity change from headwaters to mouth?

A

Stream flow gets progressively faster on their journey downstream as more water is added via tributary streams.

29
Q

What are the 3 zones of a stream?

A
  1. Erosion
  2. Transporation
  3. Deposition
30
Q

Where is erosion located on a stream?

A

in the headwater region of a stream system

31
Q

Where is transportation on a stream?

A

between the headwater region and the mouth of the stream system

32
Q

Where is deposition located on a stream?

A

right above the mouth of the stream

33
Q

What are the 3 types of sediment loads by streams?

A
  1. dissolved
  2. suspended
  3. bedload
34
Q

How are dissolved sediments characterized?

A

Sediments dissolved in solution; they are invisible; ie small grains

35
Q

How are suspended sediments characterized?

A

Sediment load in suspension; silt and clay-sized grains

36
Q

How are bedload sediments characterized?

A

Sediment load rolling along the bottom; sand, gravel, and boulder-sized grains

37
Q

What are the two types of stream channels?

A
  1. Bedrock
  2. Alluvial
38
Q

How are bedrock stream channels characterized?

A

they are cut into the underlying strata; and typically form in the headwater region; common features are potholes, steps, and pools

39
Q

How are alluvial stream channels characterized?

A

Form in sediment previously deposited in the valley; usually associated with a flood plain; channels change shape as material is eroded and transported

40
Q

What are the two major types of alluvial channels?

A
  1. meandering
  2. braided
41
Q

How are meandering alluvial channels characterized?

A

sweeping bends
Fine sediment; much-suspended load
Constant flow
Dense vegetation

42
Q

How are braided alluvial channels characterized?

A

a network of converging and diverging channels that thread among numerous islands or gravel bars
Coarse sediment (much bed load)
Variable flow
Sparse vegetation

43
Q

Where do cutbanks form?

A

on the outside of a meander; a zone of active erosion

44
Q

Where do point bars form?

A

on the inside of a meander; zone of deposition

45
Q

Where do oxbow lakes form?

A

where the meander has been cut off from joined bends

46
Q

What is the difference between local base level and ultimate base level?

A

local base level is the lowest level that a steam can erode down to in the form of a lake or reservoir
the ultimate level is the sea level

47
Q

What is a graded stream?

A

a system in equilibrium where erosional and depositional processes are balanced; there is no net erosion or deposition

48
Q

What are the depositional landforms?

A
  1. Deltas
  2. Natural levees
  3. alluvial fans
49
Q

How are deltas characterized?

A

Form when sediment-filled streams enter a large standing body of water.
stream’s forward velocity decreases; lowering its carrying capacity
coarse sediments are deposited close to the stream mouth
fine sediments are deposited at the outer edge of the delta

50
Q

How are natural levees characterized?

A

raised areas adjacent to the channel formed during flood events
they prevent water from returning to the stream channel

51
Q

How are alluvial fans characterized?

A

fan-shaped deposits of sediments at the base of mountain fronts

52
Q

If a stream breaks through a divide and captures drainage from the competing stream it is called _____.

A

stream piracy

53
Q

A _______ stream has flowing water year-round. The water table is located above the stream bed for most of the year. Groundwater is the primary source of water for streamflow. Runoff and precipitation is a supplemental source of water for a stream flow.

A

permanent (perennial)

54
Q

In curved channels. maximum velocity traces the ____ curve where the channel is preferentially scoured and deepened

A

outside

55
Q

The slope of a stream channel, expressed as the vertical drop of a stream over a specified distance (rise/run) is called the _____

A

gradient

56
Q

The volume of water flowing past a certain point in a given unit of time is called _____. It is the product of cross-sectional area and velocity.

A

discharge

57
Q

Moving from the headwaters to the mouth, in most streams, which of the following is true?
a. channel slope generally increases
b. Discharge typically decreases
c. Sediment size typically increases
d. Flow velocity generally increases

A

d. flow velocity generally increases

58
Q

Anions and cations make up a stream’s ______.

A

dissolved load

59
Q

Which of the following is most likely to be part of a stream’s suspended load?
a. gravel
b. boulder
c. silt
d. cobble

A

c. silt

60
Q

____ is the downstream movement of particles in a series of jumps or skips.

A

saltation

61
Q

The outside of a meander (cut bank) is a zone of active _____.

A

ersion

GEOL-1403 (20 decks)

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