1/7/24 EARTH SCIENCE UNIT 4 EXAM Flashcards
Erosion
the movement of weathered material
what moves sediment the most?
running water moves sediment more than any other type of erosion
what happens when precipitation falls to Earth’s surface?
some evaporate, some infiltrate into the ground and becomes ground water, and some becomes runoff
accumulation
the process in which water pools into large bodies of water (like oceans, seas, and lakes)
condensation
the process in which water vapor (a gas) in the air turns into liquid water. Condensing water forms clouds in the sky. Water drops that form on the outside of a glass of icy water are condensed water
evaporation
the process in which liquid water becomes water vapor (a gas)
precipitation
the process in which water (in the form of rain, snow, sleet or hail) falls from clouds in the sky
surface runoff
rain, snowmelt, or other water that flows in surface streams, rivers, or canals
subsurface runoff
rain, snow, melt, or other water that flows in underground streams
transpiration
the process in which some water within plants evaporates into the atmosphere, water is first absorbed by the plant’s roots then later exits by evaporating through pores in the plant
what do ground conditions determine?
ground conditions determine whether precipitation becomes runoff or groundwater
ground conditions:
1) saturated vs. unsaturated 2) vegetated vs. non vegetated 3) gradient
what happens when runoff becomes confined to a channel?
when runoff becomes confined to a channel a stream exits
what are the factors that affect stream/river velocity?
1) gradient 2) stream discharge (the amount of water in the channel) 3) stream channel shape
What is gradient?
Gradient refers to the slope of the land
what happens when gradient increases?
when gradient increases, variety increases
what happens when discharge increases?
when discharge increases, velocity increases
Why is velocity the fastest in the middle of a straight channel?
Velocity is the fastest in the middle of a straight channel because the water is forced to slow down due to friction encountered all along the channel
Where is velocity fastest and slowest in a stream meander? and why?
In a stream meander, velocity is fastest on the outside bend and velocity is slowest along the inside bend. This is because water flows straight downhill until it hits something that forces it to change direction, this causes the fastest eater to impact the outside bend stronger
Where does erosion occur in a stream meander?
water moves faster along the outside bend of a meander, erosion will occur here
cutbanks
erosion on the outside bend of a meander causes it to cut away at the bank
meander
a bend in a river channel, formed when water in the river erodes the bank of the outside of the channel
where does deposition occur in a meander?
water moves slower along the inside bend of a meander, deposition will occur here because when water slows down it drops heavier sediment it no longer can carry. this is a point bar
where does erosion occur in a meander?
the outside bend of a meander is here more erosion occurs because faster velocity, this is a cutbank
point bar
where deposition of a meander occurs
abrasion
erosion along the bed of rivers/streams makes sediments constantly bump into/rub against each other, this makes the sediment round, this is called abrasion
what is the life cycle of a stream?
a youthful stream –> a mature stream –> an old age stream
characteristics of a youthful stream:
narrow v-shaped, downcutting, swift water, steep gradient, erosion is dominant
characteristics of a mature stream:
lateral erosion begins, meanders develop floodplains develop, gradient decreases
what is lateral erosion?
sideways erosion by a river or a stream
what is vertical erosion?
when the bed of a river or a stream erodes
characteristics of an old age stream:
wide meanders and oxbow lakes, wide floodplain, little downcutting, low velocity
what is an oxbow lake?
Oxbow lakes are the remains of the bend in the river. Oxbow lakes are stillwater lakes. This means that water does not flow into or out of them
floodplain
low-lying lands next to rivers and streams
watershed/drainage basin
a watershed or drainage basin is the area of land that feeds a stream and its tributaries
tributary
a stream feeding a larger stream or a lake
how much water is found below the earth’s surface?
20 times more of Earth’s water is found below the Earth’s surface
groundwater
freshwater below earth’s surface is called groundwater
porosity
the small holes that exist between grains in a rock or a sediment
permeable
a material with interconnecting holes so that water can move through it easily
impermeable
something that water cannot penetrate (pass through)
saturated
full of liquid
water table
top of underground of porous rock that is saturated with groundwater
what does the water table not stay stable?
the water table is higher when there is a lot of rain and it is lower when the weather is dry. The water table fluctuates depending on how much water seeps down from the surface
what happens when water that sinks into the ground hits an impermeable rock layer?
water stops moving downward when it reaches an impermeable rock layer
aquifer
underground layer of porous rock or soil that is saturated with groundwater
recharge
water that enters an aquifer
how is an aquifer recharged?
rainfall seeping into the ground can recharge an aquifer
what is the main reason humans use an aquifer?
for fresh water
why is a good thing if an aquifer is close to the surface?
the aquifer could recharge quicker rather than an aquifer farther from the surface
why is it a bad thing if an aquifer is close to the surface?
the aquifer is more likely to become polluted
what could happen if humans pump too much water out of an aquifer?
the aquifer could take long to recharge and the water table could lower or cause the aquifer to run dry
what is a spring?
a fountain of hot water and steam that erupts onto the surface due to underground heat and pressure, causes ground water to go onto the surface
capillarity
the movement of water within the spaces of a porous material
porous
Something that is porous has many small holes, so liquid or air can pass through
adhesion
water is attracted to other substances
cohesion
water is attracted to water
surface tension
the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules
Why is capillarity so important to plants?
Capillary action is important for moving water around so the plants can receive the water that they need
what is the relationship between particle size and porosity?
the size of the particles does not affect porosity as long as the factors remain the same, (shape, sorting, size, packing)
what is the relationship between particle size and permeability?
as the particle size increases, permeability increases
permeability
the rate at which water can flow through sediments in the ground
porosity
the amount of space between soil particles
capillarity
the rate at which water can rise through soil particles in the ground
what is the relationship between particle size and capillarity?
as particle size increases, capillarity decreases
mechanical/physical weathering
the weathering (breaking down) of a rock due to physical processes such as temperature change
chemical weathering
the breaking down of a rock due to chemical reactions such as acid rain
ice wedging
water seeps into cracks, freezes, expands, and wedges the rock apart (physical weathering)
wind abrasion
collision of rocks with one another, scraping, grinding, and wearing away (physical weathering)
carbonation of limestone
leads to rock weathering, forms sinkholes, caverns, and disappearing streams, (chemical weathering)
root wedging
physical weathering, roots grow into rock gaps and breaks the rocks apart
exfoliation
physical weathering, the peeling of a rock due to release of pressure experienced when the rock was formed
erosion
the movement/transportation of weathered material
glacier
a large mass of ice and snow that exists year-round and moves under the influence of gravity
erratic
a large rock (boulder) that is a different rock type from the local bedrock… a glacier dropped it there
unsorted material
different sized rocks all mixed together unsorted (till), caused by a glacier
striations
chatter marks or parallel grooves in the bedrock. the scratches show the direction of ice movement caused by the abrasive action of cobbles and boulders trapped in the bottom of a glacier
glacial polish
smooth polished bedrock surfaces
how do glaciers form?
cold summers (the snow piles from the previous winter), may be at a high altitude or high latitude (above snow line or near-polar region)
how is firn formed?
buried snow gets compacted to form firn and eventually becomes glacier ice
firn
partially compacted snow that is in between the stage between snow and glacial ice
what are the two types of glaciers
alpine/valley glaciers, and continental glaciers (aka ice sheets)
valley glaciers
a glacier high in the mountains that fills in the valleys and flows downhill. the ice scrapes away at the sides of the mountain and sharpens the peaks
cirques
valley glacier landscape, semi-circular basins (bowls) found at the top of the glacier valley
arete
valley glacier landscape, a steep sharpened peak between parallel glacier valleys
tarn
valley glacier landscape, a lake within a cirque
horn
valley glacier landscape, a pyramid-shape sharp high peak formed where several glaciers begin
hanging valley
valley glacier landscape, a vertical wall formed where a tributary glacier joined a larger glacier. this will often be the site of a waterfall
u-shaped valley
valley glacier landscape, valley/alpine glaciers convert former v-shaped stream valleys into u-shaped valleys
moraines
piles of till that are deposited directly by glacier ice, moraines are composed of mixed sizes of rock and the sediment is not layered
till
sediment that is unsorted and unlayered
calving
when ice sheets melt at their southern edge, big pieces of ice fall off into the ocean
ice ages
cold periods on Earth
when do ice sheets/continental glaciers advance or retreat?
ice sheets advance during ice ages and retreat during inter-glacial periods (like now)
ice front
the front of the ice
drumlin
a king inverted canoe-shaped hill of till usually found in groups, points in the direction of ice flow
kettle lake
a lake formed by a buried block of curved ice that has melted and created a depression
esker
a long strip of sediment that is deposited by the rivers of melt-water running out the ice front
kame
a cone-shaped pile of sorted, stratified sediment deposited by rivers of meltwater running along the top of the glacier and plunging down the ice front onto the ground
outwash plains
an erosional and depositional surface formed by meltwater coming from the glaciers
terminal moraine
a long pile of till deposited at the farthest extent of the ice front
