Geography 1 (41100). Prof. Dean . Wint., Jan 17, 2012 . Lect and Chp 9 & 17
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Chapter 9
The Hydrosphere
I. The Hydrologic Cycle
a. Bulk of Earth’s moisture (99%) is in storage in oceans, lakes, rivers,
glacial ice or rocks beneath the surface.
b. The remaining fraction (1%) is involved in a continuous sequence of
movement and change.
c. Movement is the hydrologic cycle.
II. The Hydrologic Cycle
a. Three primary movement types
i. Surface to air
1. Ocean evaporation
2. Vapor remains in air for a short time
ii. Air to surface
1. Precipitation – 78% falls on oceans and 22% on land.
2. Precipitation is the same as evaporation over long time
scales.
iii. Movement beneath the surface-runoff
1. Water collects in lakes and rivers and either penetrates
ground or runs off it sloped
2. Becomes part of underground water supply
3. Reemerges as springs or becomes part of rivers and
streams
iv. Residence Times
III. The Oceans
a. Vast majority of surface is oceans
b. Number of oceans
i. Four principal parts
1. Pacific-largest, occupies 1/3 of total Earth surface area
2. Atlantic-less than half the size of the Pacific
3. Indian-slightly smaller than Atlantic
4. Arctic-small and shallow
c. Smaller bodies-seas, gulfs, and bays
d. Characteristics of ocean waters
Geography 1 (41100). Prof. Dean . Wint., Jan 17, 2012 . Lect and Chp 9 & 17
i. Chemical composition
1. Sodium and Chlorine
2. Salinity
ii. Increasing acidity
1. Carbon dioxide absorbed by ocean water creates
carbonic acid
2. Affects the ability of microscopic creatures to build
shells and exoskeletons
iii. Temperature
1. Decreases with increasing latitude
2. Ranges from near 80F to near 28F
iv. Density
1. High temperature means low density
2. High salinity means high density
IV. Movement of Ocean Waters
a. Causes of tides
i. Gravitational attraction of Moon (lunar tides) and Sun (solar
tides)
ii. More gravitational force on the side of Earth facing the Moon.
iii. More centripetal force on opposite side to keep Earth in orbit
iv. Two bulges form on opposite sides of the planet.
v. Two tidal cycles in 25 hours
vi. Flood tide and high tide
vii. Ebb tide and low tide
b. Monthly tidal cycles
i. Tidal range-difference in high and low tides
ii. Spring tides- the highest tide
iii. Neap tides- the lowest tide
c. Global range of tides
d. Currents
i. Subtropical gyres develop from surface wind patterns
ii. Deep ocean circulations
1. Result from differences in salinity and temperature in
deep ocean water.
2. Thermohaline circulation
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Geography 1 (41100). Prof. Dean . Wint., Jan 17, 2012 . Lect and Chp 9 & 17
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3. Water in northern latitudes is colder and higher salinity,
so it sinks.
iii. Global conveyer-belt circulation
e. Waves
i. Disturbances to the sea surface
ii. Little forward progress is observed
iii. Wave breaking can result in shifting of water
V. Permanent Ice-The Cryosphere
a. Cryosphere
i. Second greatest storage of Earth’s water
ii. Two groups; ice on land and ice in water
iii. Approximately 10% of Earth’s surface is ice
iv. Different names
1. Ice pack
2. Ice shelf
3. Ice flow
4. Iceberg
v. Cryosphere
1. Largest ice pack covers most of the Arctic ocean surface
2. Several large ice shelves attached to Antarctic
3. Large ice floes form off of Antarctica
vi. Permafrost
1. Permanently frozen ground ice
VI. Surface Waters
a. Represent only 0.02% of the world’s total moisture
b. Numerous surface water types
c. Lakes—bodies of water surrounded by land
i. Small lakes are called ponds
ii. Lake Baykal in Siberia is the largest lake by volume
d. Saline versus freshwater lakes
e. Ephemeral lakes (only contain water sporadically)
f. Two conditions required for lake formation
i. Natural basin with restricted outlet
ii. Sufficient water to keep basin filled
g. Most are relatively short-lived
Geography 1 (41100). Prof. Dean . Wint., Jan 17, 2012 . Lect and Chp 9 & 17
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h. Human alteration of natural lakes
i. Irrigation
ii. Water diversion projects
iii. Reservoirs
1. Artificial lakes used for hydroelectric power, municipal
water, and stable agriculture
i.
Swamps and Marshes
i. Flattish places that are periodically submerged and shallow
enough to permit plant growth
ii. Swamps grow trees
iii. Marshes grow grasses and rushes
j.
Rivers and Streams
i. Streams smaller than rivers
ii. Geographers call all running water streams
iii. Allow for drainage of land surface water towards oceans
iv. Drainage basins
VII. Underground Water
a. Water beneath land surface worldwide
b. More than half found within 800 meters of the surface
c. Precipitation or water basins are the sources
d. Quantity hold depends on
i. Porosity
ii. Permeability
e. Aquifers and aquicludes
f. Zone of aeration
i. Topmost band in underground water supply
ii. Water amount fluctuates rapidly with time.
g. Zone of saturation
i. All pore spaces filled with water, called groundwater
ii. Top of the zone is the water table
iii. Water table intersects surface, water flows out (lakes, swamps,
etc.)
iv. Well water drawn faster than replenished creates a cone of
depression.
v. Lower limit has absence of pore spaces
Geography 1 (41100). Prof. Dean . Wint., Jan 17, 2012 . Lect and Chp 9 & 17
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h. Zone of confined water
i. Zone that exists in some regions that is below the region of
impermeable rock below the zone of saturation
ii. Pressure at the great depth of the water will cause water to
rise to piezometric surface.
iii. Artesian well versus sub-artesian
i.
Waterless zone
i. Pressure too great to sustain water
j.
Groundwater mining
i. Accumulation of groundwater is slow, but human use is rapid
ii. The Ogallala Aquifer
1. Water table drops with increased use
2. Numerous wells have been tapped
3. Unsustainable situation.
Chapter 17
Karst and Hydrothermal Processes
I. The Impact of Solution Processes on the Landscape
a. Mechanical effects of underground water have limited topographic
influence
b. Water’s solvent properties allow it to dissolve certain chemicals from
rock.
c. Hydrothermal vents
II. Solution and Precipitation
a. Water in its pure form is a poor solvent
b. Chemical impurities make water a good solvent of a few underground
minerals.
c. Carbonic acid.
d. Dissolution
i. Most effective on carbonate sedimentary rocks (i.e., limestone)
ii. These are most notable dissolution processes
iii. Occurs more rapidly in humid regions
iv. Possible role of sulfuric acid
e. Role of bedrock structure
Geography 1 (41100). Prof. Dean . Wint., Jan 17, 2012 . Lect and Chp 9 & 17
i. Profusion of joints allows for groundwater penetration
f. Precipitation processes
i. Mineralized water trickles along cavern roof or wall
ii. Reduced air pressure precipitates mineral material
iii. High mineral content in hot springs
g. Large openings beneath the Earth’s surface that result from solution
processes
h. Often found in areas with massive limestone deposits
i.
Two principal stages
i. Initial excavation
ii. Decoration stage: speleothems
iii. Stalactites and stalagmites
III. Karst Topography
a. Topography that results from underground dissolution
b. Typical landforms
i. Sinkholes
ii. Disrupted surface drainage
iii. Underground drainage networks
c. Sinkholes
i. Rounded depressions that form from dissolution of surface
carbonate rocks
ii. Collapse dolines
iii. Wide range of sizes
iv. Fundamental karst unit of erosion and weathering
v. Chains of sinkholes: uvala
vi. Tower karst
vii. Disappearing streams and swallow holes.
IV. Hydrothermal Features
a. Geysers and Hot springs
b. Hot Springs
i. Water heated by magma
ii. Forced upward from pressure resulting from heating
iii. Resulting topography from hot springs.
iv. Algae growth
c. Geysers
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Geography 1 (41100). Prof. Dean . Wint., Jan 17, 2012 . Lect and Chp 9 & 17
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i. Intermittent hot spring
ii. Accumulation of superheated water and steam builds pressure
iii. Tremendous heat required for geyser formation
iv. Variable eruption times
v. Variable deposits, most are sheets of deposits scattered
irregularly over ground
d. Fumaroles
i. Surface crack connected to a deep-seated heat source
ii. Little water drainage
iii. Water that is drained is converted to steam
iv. Steam issuing vent, either continuously or sporadically
e. Hydrothermal features in Yellowstone
i. 225 geysers
ii. Volcanic bedrock materials
iii. Shallow magma chamber, mantle plume (heat source)
iv. Copious summer rain and winter snowmelt (water source)
v. Numerous fractures and weak zones from earthquakes
vi. Geyser basins in same watershed on west side of park
vii. Geyser basins drained by three rivers
viii. Geyser basins have extensive geyserite
ix. Mammoth Hot Springs Terraces