Geology

describe the hydrolic cycle

 

The hydrologic cycle begins with the evaporation of water from the surface of the ocean. As moist air is lifted, it cools and water vapor condenses to form clouds. Moisture is transported around the globe until it returns to the surface as precipitation. Once the water reaches the ground, one of two processes may occur; 1) some of the water may evaporate back into the atmosphere or 2) the water may penetrate the surface and become groundwater. Groundwater either seeps its way to into the oceans, rivers, and streams, or is released back into the atmosphere through transpiration. The balance of water that remains on the earth’s surface is runoff, which empties into lakes, rivers and streams and is carried back to the oceans, where the cycle begins again

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likelihood of sheet flow runoff depends on the infiltration of the soil:

;

what are some of the characteristics of it

(5)

soil texture

slope of land

intensity and duration of rainfall

prior wetted condition of soil

nature of vegation cover

what are drainage basins?

;

how is it seperated?

area the contributes water to a river system.

;

seperated by a divide ranging in scale from a ridge to a contiental divide

what are the 3 zones of a river system?

;

can all 3 happen in one zone?

erision

sediment transport

deposition

;

;

yes, but one will always dominate

;

what is laminar stream flow?
slower and straight
what is turbulent stream flow?
faster not straight
what determines the velocity of streamflow?

gradient

shape, size and roughness

discharge

what is graident?
change in elevation (vertical drop)/distance
the steeper the gradient….

the more energy avaible

;

-faster speed

what are potholes
rounded depressions on the bottom of the river bed
stream erosion is…
the ability to accumlate and transport soil/ weathered rock aided by rain drops that knock sedimentary particles loose.
what are the;3 ways of transporting materials and describe them or give an example

dissolved load-; ex. calcite ions

;

suspended load-(floating particles) ex. stokes law[settling velocity, sediment size vs stream velocity

;

bed load(dragged particles)

sediment deposition deposition depends on which 2 tings and descirbe them

;

sorting- deposition; of particles of a similar size together

;

alluvium-any stream-depositied sediemnts

what are the characteristics of Bed rock

steep high gradient with fast moving water

ex is the grand canyon

what are charactericts of alluvial?

;

braided or meandering streams

ex mississippi river valley

braided streams are
wide and shallow streams consisting of smaller interwoven streams.; often through course sediment

be able to locate a meander and ox bow on a digram.

with the meander know the erosion of the cut banks

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the downward limit to stream erosion (lowest elevation) in which a stream can erode its channel is known as…

;

gradient stream can neither erode or deposit sediments at this level.

base level

down cutting is the dominant activity of what?

;

;

valley deepening
the most prominant feature of V-shaped valleys are
rapids and waterfalls

Velley widening:

what are flood plains

lateral erosions

valley widening:

terraces

remains of former floodplains left as flat elevated surfces

valley widening:

what are deltas

streams enetering an ocean or lake

valley widening:

natural levees

sediment carried by river flows into a flood plain and left there as the water retreats.

valley widening:

alluvial fans

fan shaped deposits of alluvium at the mouth of the valley

;

forms at the base of mountains.

what is groundwater and where is it located

largest resivoir of fresh;water redily avaible to humans.

;

its found in pore spaces in sediment or in bed rock fractures

distribution of groundwater:

;

zone of soil moisture is

some water is held near the surface

distribution of groundwater

;

zone of saturation is

remaining water precolates down to fill all pore spaces avaible within the sediment

distribution of groundwater

;

water table is

upper limit of the zone of saturation

gaining or losing

;

which occurs at high water tables?

which occurs at low water tables?

;

;

;

gaining=high

losing=low

what are the factors that effect water storage and movement

porosity

permeability

aquitards (impermeable layers)

aquifers (permeable layers)

wells create _______when water is removed
cone of depression
glaciers are part of what 2 cycles?
hydrolic and rock
what is a glacier
thick mass of ice the origonates on land from the accumlimation, compaction and recrystalization of snow.

types of glaciers

;

-exists in mountanious ares

flow down a valley from an accumulation center at its head

valley (alpine) glacier

types of glaciers

;

-exist on a larger scale then valley glaciers

two major ones on earth are over greenland and antartica

;

ice sheets

;

often called contential ice sheets

all types of glaciers (5)

;

valley (alpine)

ice sheets

ice caps

outlet glaciers

piedmont glaciers

what would happen if the ice melted on earth
sea level would rise 60-70 meters
slightly more then what % of the worlds water is tied up in glaciers
2%
what are the characteristics of the Antartic ice sheet

-80% of the worlds ice

-nearly 2/3 of earths freshwater

covers almost 1 1/2 times the area of the United States

where do glacies form
areas where more snow falls in winter then it melts during the summer

how does a glacier form

5 steps

-air infiltrates snow

-snowflakes become smaller, thicker, and more spherical

-air is forced out

-snow is recrystallized into a much denser mass of small grains called firn.

-once the thickness of ice and snow exceed 50 meters, firn fuses into a solid mass of interlocking crystals—-glacier ice

2 tyoes of glacier flow & describe them.

-plastic flow:occurs within the ice…under pressure, ice behaves as a plastic material

 

-basal slip:  entire mass slipping along the ground…most glaciersare thought to move this way

movement of glaciers is refered to as…..

 

zone of fracture is occurs where and is what

– as flow

 

-occurs in the uppermost 50 meters

tension causes crevases to form in brittle ice

glaciers form at what zone
zone of accumlation
glacires erode the land in two ways, descibe how

-plucking: lifting of rocks

-abrasian: rocks within the ice act like sandpaper to smooth and polish the surface below.

erosioanl features created by glacial erosion in valleys

(9)

 

-glacial troughs

-truncated spurs

-hanging valleys

-pater noster lakes

-tarns

-fjords

-aretes

-horns

 

types of glacial drift

till

straified drift

till is material that is depositied directly over ice

 

stratified drift sediments laid down by glacial meltwater

indirect effects of Ice Age Glaciers

(6)

-forces migration of plants and animals

-changes in stream courses

-rebounding upward of the crust in former centers of ice accumlation

-worldwide change in sea level

-climatic changes

-pluvial lakes

causes of glaciation

 

the Milankovitch Hypothesis

(4)

 

-shape(ecentricity) of earths orbit varies

-angle of earths axis(obliquity) changes

-earths axis wobbles (precession)

-changes in climate over the past several hundred years are closely associated with variations in the geometry of earths orbit

dry climates are composed of —% of earths land surface
30%
what and where are low latitude deserts

–subtropical heights

-as air sinks it compresses and warms

-very low relative humidity

 

–tropics of cancer and capricorn

what and where are mid-latitude deserts

example?

–not associate with subtropical high pressure systems

 

-occur in the middle of a large landmass on the leeward side of mountain ranges

 

ex. gobi desert

rainshadow deserts

what is the rainshadow effect

-wind is forced to rise s it reaches a mountain range

–air cools then condenses

–moisture is precipatated out on the windward side before cresting the mountain

— as air sinks on leeward side, it compresses and warms but is dry.

these are characteristics of what

-short lived

infiltrate/evoprate before water can reach the ocean

-only carry water in response to rainfall

lasts only a few hours to a few days

–ephemeral streams (deserts)

desert rainfall

1.rain occurs as  ___ ____

2. most erosion is done by ____ ____

3. vegatation is sparse so _____ is unhindered and ___ ___ are common

1.heavy showers

2. running water

3. runoff,  flash floods

how is transportation of sediment by wind different then running water?

(2)

 

— wind is less capable of picking up and transporting course materials

— wind is not confined to channels and can spread sediment over large areas

what are some characteristics of Dune (a form of wind deposit)

-mound or ridges of sand

-often asymetrically shaped

-windward shape is gently inclined and the leeward slope is called slipface

what are characteristics of Loess ( type of wind deposit)

blankets of windblown silt

-primary sources are deserts and glacial outward deposits

– extensive deposits occur in china and the central United States.

flat platform composed of sand and marked by change in a slope at seaward edge is

 

the wet sloping surface the extends from the berm to the shoreline

 

an accumlation of sediment found along the landward margin of an ocean or lake.

berm

 

beach face

 

a beach

wind generated waves provide most of the
energy that shapes and modifies shorelines
where do waves derive their energy and motion from
wind

parts of a wave

crest

trough

 

measurements of wave

wave height

wave length

wave period

crest- top of the wave

trough- is the low area between waves

 

wave height- distance between a trough and crest

wave length- horizontial distance between crests ( crest to crest)

wave period-  time interval between the passage of the 2 sucessive crests.

height length and period of a wave all depend on

wind speed

length time wind has blown

fetch (distance that the wind has traveled across open water)

wind erosion is caused by

wave impact and pressure

abrasion by rock fragments

what is light wave activity

swash is likely to soak into the beach, decresing the amount of backwash

 

net movement of sand up beach face toward berm

what is heavy wave activity

beach likely to be saturated

berm erodes because backwash is so strong

net movement iof sand is down the beach face

waves approach the shore at an ___

 

what happens to a wave as it reaches shallow water with a smooth sloping bottom

angle

 

they are bent and tend to become parallel to the shore

consequences of wave refraction

wave energy is concentrated against the sides and ends of headlands

wave attack is spread out and weakened

over time wave erosion straightens an irregular shoreline

waves along the beach moving in a zig-zag pattern is known as a ____

 

drift
features of a shoreline vary depending on several factors like:

-rocks along the shore

-currents

-wave intensity

-whether the coast is stable, sinking, or rising

shoreline wave erosion: (2)

 

features associated with headlands: (2)

-wace-cut cliffs

-wave cut platforms

 

 

–sea arch

–sea stack

what are spits
elongated ridges of sand extending from the land into the mouth of an adjacent bay

_____ is a sand bar that completly crosses a bay

 

______ is a ridge of sand that connects an island to the mainland or another island.

baymouth bay

 

tombolo

barrier islands are mainly located ?

 

what are barrier islands?

-along altantic and gulf coasts

 

-low ridges of sand that run parallel to the coast 3 to 30 kilometers offshore

4 basic responses to shorline erosion

jetties: extend into ocean at the entrance to rivers and harbors

 

groins:  contsructed at a right angle to the beach to trap sand

 

breakwaters: protect boats from the force of large breaking waves

 

seawalls: stops waves from reaching the beach areas behind the wall

what is the most violent storm on earth
hurricanes
what is needed for a storm to be considered a hurricane?

wind speed more then 74 mph

rotary cyclonic rotation

profile

form between the latitudes of 5 and 20 degrees

emergent coasts develop because of….

 

2 features

an uplift of an are or a DROP in sea level

 

-wave-cut cliffs

-wave-cut platforms

submergent coasts are caused by…

 

2 features

land adjacent to the sea or a RISE in sea level

 

-highly IRREGULAR shores

-estuarires-drowned river mouths

what makes up a spring tide

-occurs during new and full moons

-produce esp high and low tides

-large daily tidal range

what makes up neap tides

-occur during the first and third quarters of the moon

-gravitional forces of the moon and sun are offset

-daily tidal range is least