Final Flashcards
(104 cards)
1
Q
Atmosphere and Climate
A
70% of earth’s surface is water
80% of southern hemisphere
2
Q
Composition of Earth’s Atmosphere
A
Nitrogen, Oxygen, Argon all make up 99.9%
Carbon Dioxide is next up…..401.18ppm
Unique in our solar system: oxygen and water vapor
3
Q
Structure of Atmosphere
A
TOP TO BOTTOM
4
Q
Thermosphere
A
90km-120km
Magnetosphere
5
Q
Mesosphere
A
50km-90km
Ionized gases
6
Q
Stratosphere
A
20km-50km
ozone layer
7
Q
troposphere
A
0km-20km
weather and clouds
`
8
Q
Insolation
A
Earth's climate is fundamentally controlled by the way solar radiation interacts with Earth's surface and atmosphere
Mostly in the visible
spectrum
Reradiated as
infrared
9
Q
Absorption
spectra
A
Heat is trapped by
greenhouse gases
(mostly CO2)
10
Q
Greenhouse gases:
A
absorb longwave radiation
and emit some of it back to the Earth as heat.
11
Q
Keeling Curve
A
Long term rise
• draw down in northern hemisphere summer
12
Q
Climate
A
the average weather conditions
during the year.
13
Q
greenhouse effect
A
The trapping of heat in the Earth’s atmosphere
by carbon dioxide and other greenhouse gases, which
absorb infrared radiation; somewhat analogous to the effect of glass in a greenhouse
14
Q
coriolis effect
A
air moving north from the equator to the pole deflects to the east, and in each hemisphere, three convection cells develop (the Hadley, Ferrel, and polar cells).
15
Q
hadley circulation
A
The name given to the low-latitude convection
cells in the atmosphere.
16
Q
trade winds
A
Thus, between the equator and 30°N, surface
winds come out of the northeast, and are called the northeast trade winds, so named because they once carried trading ships westward from Europe to the Americas.
17
Q
doldrum
A
But winds along the equator are very
slow, because the air is mostly rising. Ships tended to be becalmed in this belt
18
Q
Prevailing westerlies
A
prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and tend towards the poles and steer extratropical cyclones in this general manner.
east to west
19
Q
Sea surface temperatures
A
Warmest at equator (28°C [82°F])
Freezing at high latitudes
Mean annual temperature is 17°C (63°F)
20
Q
Sea surface salinities
A
Oceanic = 35 ‰ (ppt) • Brackish = Lower than marine • Bays, lagoons • Hypersaline = Higher than marine • Hot arid climates
Atlantic Ocean is saltier
• Mediterranean
Isthmus of Panama
21
Q
surface zone
A
0-200 meters or 650 feet
2% of ocean water
22
Q
major depth zones in the ocean
A
***salty, cold water is dense.
general rule lower temp, more salinity, more density
thermocline + halo cline = pycnocline
23
Q
pycnocline - 18%
A
200m - 1000m(3300 ft)
24
Q
deep zone 80%
A
1000m -5000m (14000+ feet)
25
Thermohaline circulation
During thermohaline circulation, denser water (cold and/or saltier) sinks, whereas water that is less dense (warm and/orless salty) rises
Sinking of North Atlantic Deep Water (NADW) drives a
"conveyor belt" ocean circulation
```
The combination
of surface currents and
thermohaline circulation,
like a conveyor belt,
moves water and heat
among the various ocean
basins
```
26
Atlantic Water Masses
Like the atmosphere, oceans are stratified
– by temperature (cooler at bottom)
– by salinity (saltier at bottom)
• Atlantic Ocean is more saline than Pacific
27
DSDP - Deep Sea
| Drilling Project
Launched in 1968 and sailed for 15 years
• First research vessel designed for drilling and taking core samples from deep ocean floor
• Over 60 miles of core at 624 different sites
• Scientific accomplishments include definitive
proof of Sea Floor Spreading
28
Ocean
| Drilling Program
Successor to Deep Sea Drilling Project
• international effort
• drillship: JOIDES Resolution
• 110 expeditions and 2000 deep sea cores
• explore and study the composition, structure,
and history of the Earth's ocean basins
29
IODP
```
Multiplatform:
• Nonriser (revamped Resolution
- Run by US)
• Riser (Chikyu, run by Japan)
• Mission Specific (Europe..., special needs platforms- shallow water, ice-covered)
```
30
Passive margin
Broad continental shelves, like that of eastern North
America, form along passive continental margins, margins
that are not plate boundaries and thus lack seismicity
31
Active margin
a margin that coincides with a plate boundary and
| thus hosts many earthquakes
32
Trench
convergent boundaries where lithospheric plates subduct into the mantle
long, relatively narrow
- deepest parts of ocean
(most >8 km; 11 km) - most are in Pacific
33
Continental shelf
a relatively shallow portion of
the ocean in which water depth does not exceed 500 m,
fringes the continent.
nearly flat from shoreline to continental slope; 0.1 to 0.06° slope (1:1000)
• < 200 m deep, may extend 100’s km offshore
34
Coastal plain
a flatland that merges with the continental
shelf, as exists along the Gulf Coast and southeastern
Atlantic coast of the United State
35
Epicontinental sea
A shallow sea overlying a continent.
36
Graded shelf
Moves from coarse to fine
sand, muddy sand, sandy mud, mud
37
Continental shelf break
around 150 meters deep slope
75 meters distance offshore
38
contiental slope
Below the slope is the continental rise, which finally merges into the deep ocean floor, the abyssal plain. The continental shelf and the slope are part of the continental margin.
39
Submarine canyons
cut into continental slope
40
Turbidity currents
A submarine avalanche of sediment and
| water that speeds down a submarine slope
41
Turbidites
A graded bed of sediment built up at the base of a
| submarine slope and deposited by turbidity currents
42
Continental rise
The sloping sea floor that extends from the
| lower part of the continental slope to the abyssal plain.
43
Abyssal plain
A broad, relatively flat region of the ocean that
lies at least 4.5 km below sea level.
Away from:
• tectonic processes
• waves and tides at the sea surface • turbidites coming off the shelf
*Flattest surface on the Earth
- Forms LARGEST part of ocean
- Contains submerged volcanoes called seamounts.
44
Lithogenic
derived from land
Terrigenous: derived from continents (turbidites)
– Pelagic clay “red clay” barren regions below the CCD with only eolian, volcanic, and cosmic sources for mud
Lithogenic sediments
Near continental margin
1-10 cm/1000 yrs
Red or pelagic clay
(eolian, volcanic, and cosmic sources for mud)
1 mm/1000 yrs
45
Biogenic
derived from organisms
– Carbonate Ooze 48% of the ocean floor, accumulates
above the CCD
– Siliceous Ooze sediments are concentrated in regions of upwelling ocean currents
46
Hydrogenic
precipitated from water
Manganese nodules - are rock concretions on the sea bottom formed of concentric layers of iron and manganese hydroxides around a core.
Very slow growth - a few centimeters per million years
47
Distribution of carbonate sediments
* Dilution - by other particles
* Destruction - calcium carbonate dissolves
* Productivity- reproduction of organisms
48
sinkhole
circular depression
49
Hydrologic Cycle
Run-off
Evaporation
Transpiration
Infiltration
50
Reservoir
any environment where water is stored
51
why is groundwater such a valuable resource?
Abundant - 70 times more fresh water below ground than above it.
Constant - Groundwater is available even during dry periods.
Widespread - Groundwater can flow from humid environments to where it is needed in dry regions.
52
Aquifer
sediment/rock through which water flows easily
53
Porosity
the percent of the total volume of a rock that consists of pore spaces
A very porous rock contains a large proportion of pore space
54
Aquifer
sediment/rock through which water flows easily
*sand or gravel
• weathered limestone
• fractured igneous rock
55
Examples of rock types and porosity
most limestone, clay
least - shale, igneous, metamorphic
56
what makes a difference in porosity
```
* sizes and shapes of particles
• compactness of the arrangement
• gravels have large openings but the
stuff is usually of many sizes – the pores
get clogged
• cement
• igneous and metamorphic rocks have
low porosity except where they are fractured
```
57
Zone of aeration
open spaces are normally
| filled with air
58
Water table
top of saturated zone
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Zone of saturation
spaces are filled with water
60
Permeability
the capacity for transmitting fluids
Sands have high permeability
Clay/Shale - little/no permeability
61
Fractured Shale
has secondary permeability
| due to fractures
62
Weathered joints and bedding-plane fractures transmit large amounts of water.
Weathered joints and bedding-plane fractures in Paleozoic limestone transmit large amounts of water at rapid rates.
63
Confining bed
Sediment/rock that restricts the flow of water
CLAY
64
unconfined
Intersects the surface
65
confined
bracketed by confining beds
ex: artesian aquifer
66
Perched Water Table
More than one water table
67
Perched Water Table
More than one water table
68
Geologic work of Groundwater
Groundwater combines with carbon dioxide to form carbonic acid
Limestone is quite easily dissolved in water containing a small amount of carbonic acid.
H2O + CO2 = H2CO3
Water + Carbon dioxide = Carbonic acid
69
Karst Topography
landscape in which caves and sinkholes are so numerous that they form a peculiar topography characterized by:
ONLY WHERE CARBONATES OCCUR
* Many small, closed basins.
• Disrupted drainage pattern.
• Streams disappearing into the ground.
• Streams reappearing as large springs.
70
Stalactite
icicle like cone
71
Stalagmite
Upward pointing cone
72
Columns
when the stalactites and stalagmites merge
73
geologic materials makes the best confining bed
shale
74
Gravity Driven Flow
Groundwater infiltrates during a rainfall
Recharge – where groundwater is replenished • Discharge – where groundwater flows from the surface
75
Springs
Location where the water table intersects the ground surface.
76
D'arcy's Law
change in H = h1 - h2
Change in H / distance between two points
77
hyradulic gradient (slope of water table)
The potential energy available to drive the flow of a given
volume of groundwater at a location
* * slope of the water table (steeper = faster)
* ** permeability (higher = faster)
78
Rates of groundwater movement
• Groundwater tends to move slowly, as seepage through pores of soil, rock, unconsolidated material, etc.:
– from 0.03 meters/year (slow) to 0.3 meters/day (fast), a difference of > 3 orders of magnitude
• For comparison, rivers flow at rates around 0.3 to 3 meters/second or over 4000 meters/day for even a slow river
79
Gravity Driven Flow
Repeated rainfall prevents the water table from assuming a level surface
In order for the groundwater table to remain constant the rate of recharge must be equal to the discharge rate
80
Wet Period
High water table
81
Dry Period
lower water table
82
Cone of depression
a conical shaped depression of the water table due to pumping
83
Artesian well
Well water pumped to holding tank
Gravity maintains pressure from there to the faucet
a well in which water rises above the aquifer.
Sometimes pressure can lift the water above the ground and water will flow
84
Wells
Dug or drilled through zone of aeration + below water table Water is then lifted out or pumped out
85
Drawdown due to pumping
Cone of depression
Water table can drop below useable depth through excessive pumping
Subsidence
Saltwater intrusion
86
Subsidence
Over pumping can cause grains to settle
ground crack; fissures develop
87
Saltwater intrusion
Salt-water intrusion - pulling salt-water into fresh-water aquifers
88
Saltwater intrusion
Salt-water intrusion - pulling salt-water into fresh-water aquifers
89
Hydrologic cycle
* Powered by sun
• Atmosphere provides the link
• Water from oceans carried onto land
90
Infiltration
water that soaks into the ground
source of
ground water
91
Sheetwash
a film of water a few millimeters thick that covers a ground surface
goes into channel
92
Drainage Basin
Drainage basin or watershed - region drained by a single river or river system
93
Longitudinal Profile
Stream features change from steeper at the headwaters to flatter at the mouth
94
Base level
lowest elevation a stream bed can reach at a given locality
Streams erode their channel down to base level.....waterfall, lakes are both examples
SEA LEVEL IS ULTIMATE BASE LEVEL
95
Discharge
Discharge = Velocity * Area
Area = width * depth
96
Hjulstrom’s Curve
Fluid velocity determines the size of particles that can be moved
higher velocities are needed to erode
1) large particles and 2) cohesive clay & silt
97
Competence vs. capacity
Fluid velocity determines the size of the particles that can be moved
higher velocities are needed to move large particles
Large gravel moves during flood
98
Stream Geomorphology
Two basic fluvial styles:
meandering (single channel)
braided (multiple channel)
99
Braided stream
A channel that consists of a network of small channels separated by small and often temporary islands called bars
Braided streams form when the river has a large sediment load
100
Meandering river
Velocity effects on sedimentation and erosion:
– Cutbanks on the outside of bends (high velocity) (max erosion)
– Point bars on the inside of bends (low velocity) (max deposition)
101
Levee
The boundary between channel and floodplain may be the site of a natural levee – a broad, low ridge of sediment built along the side of a channel
102
Levees form when sediment-laden floodwater overflows the channel and slows as it moves onto the floodplain.
The area adjacent to and outside of the channel serves as an overflow area for excess water and sediment
103
oxbow lake
The meander that has been cut off
is called an oxbow lake if it remains filled with water, or an
abandoned meander if it dries out (
104
Deltas
Deltas develop where the running water of a stream enters
standing water, the current slows, the stream loses
competence, and sediment settles out. Geologists refer to
any wedge of sediment formed at a river mouth as a delta,
fluvial deposit is generated where a river meets the ocean
