Earth Science Test #4

Stream

water flowing downhill due to gravity confined to a channel

(rivers, streams, creek, etc. = streams)

Hydrologic Cycle

illustrates the circulation of Earth’s water supply

Precipitation

material falling to the ground because of gravity

(rain, sleet, snow, etc.)

Infiltration

seeping into the ground

Evaporation

process of a liquid turning into a gas

Transpiration

water moving through plants

(also called evapotranspiration when it evaporates from the leaves)

Runoff

water moving across the surface

Condensation

gas turning into a liquid

Meandering Stream

meanders through the landscape; soft material

Braided stream

multiple sections confined to one channel; glacial or mountain areas

Tributary

smaller stream that flows into a larger stream

What are the parts of a stream?

stream bed - the bottom of the stream

channel - where the water is

banks - the edges of a stream

head - start of stream

mouth - end of stream

Drainage basin

land area that contributes water to a river system

Drainage divide

separates drainage basins (a high spot that divides drainage basins)

• ex: Continental divide - divide in the U.S. and Rocky Mountains

Gradient

also called slope

Discharge

volume of water flowing in the stream

(generally expressed as cubic feet per second or cubic meters per second)

Dissolved load

ions dissolved in the stream; not solid

Suspended load

solid particles floating in the stream

Stream load

transported material is called this

Bed load

solid material in contact with the stream bed

Traction

sediment that rolls along the stream bed

(ALWAYS in contact with the stream bed)

Saltation

sediment that skips along the stream bed

(SOMETIMES in contact with the bed & sometimes not)

Competence

maximum particle size

Capacity

maximum load

Deposition

sediment that is not being moved

Delta

• sediment deposited when a stream flows into another body of water

• in a fan shape

• generally sand

Alluvial fan

• sediment deposited when a stream flows on to a flat surface

• (not in water ex: flows down a mountain to a valley in a dry climate)

• in a fan shape

Natural levee

• sediment deposited as a stream overflows its channel

• form parallel to the stream channel

Base level

lowest point a stream can erode to

Floodplain

area adjacent to the stream that typically floods

Meander

curves in the stream

Cutbank

• outside of bend

• where erosion occurs

Pointbar

• inside of bend

• where deposition occurs

Oxbow lake

cutoff meanders filled with water

Meander scar

cutoff meander not filled with water

Flood

when a stream overflows its banks

Hydrograph

it shows stage measuremnets for the gauging station

Recurrence interval

the average time in years between floods of the same size

Groundwater

water beneath the surface

(largest liquid freshwater reservoir for humans)

Sinkholes

surface depressions that are formed by dissolving bedrock and cavern collapse

Caverns

caves formed by dissolving rock beneath Earth’s surface; formed in the zone of saturation

Zone of aeration

pore spaces in the soil material are filled mainly with air but can have some water, especiallly after a rain event

Unsaturated zone

another word for zone of aeration

Zone of saturation

all pore spaces in the material are filled with water

(water within the pores is groundwater)

Water table

the upper limit of the zone of saturation

Porosity

percentage of pore spaces

Pore space

spaces between particles, like the space between individual sand grains

Permeability

• ability to transmit water through connected pore spaces

• the interconnectedness of pore spaces

Aquifer

• permeable layer

• high porosity and high permeability

• Ex: sandstone, conglomerate, limestone, highly fractured igneous or metamorphic rock)

Aquitard

• impermeable layer

• low permeability and porosity

• Ex: shale, unfractured igneous or metamorphic rocks

Confined aquifer

• confined between two aquitards

• very limited area at surface to be refilled by rain events

• most water in these were put here during the last glacial period

Recharge zone

area at the surface where water infiltrates the aquifer by rain events

Unconfined aquifer

open to the surface that can be refilled by rain events

Artesian well

water in the well rises higher than the initial groundwater level (under pressure)

Perched aquifer

• suspended above the water table

• also known as a false water table (because water will “run out” for wells drilled here)

Hot springs

heated by cooling of igneous rocks or magma beneath the surface

Geysers

intermittent hot springs

Ex: Old Faithful in Yellowstone National Park

Saltwater intrusion

• when salt water gets into a groundwater source

• a well near the ocean can cause unwanted saltwater to come up into the well since freshwater is less dense than saltwater

Groundwater overdraft

This has caused a drop in the water table of up to 70 meters

(The Ogallala Aquifer case study)

Drawdown

lowering of the water table (like sucking water up a straw)

Cone of depression

the larger the well, the larger this is.

Land Subsidence

caused by its withdrawal

(land compacts when it no longer has water &.will no longer hold as much water as it did before)

Karst Topography

terrain formed by dissolving rock at, or near, Earth’s surface

(sinkholes, caves, or caverns, etc.)

Point source pollution

can tie back to a specific place

Ex: a chemical factory leak, an oil spill from a tanker, etc.

Nonpoint source pollution

cannot tie back to a specific place

Ex: nutrients from farmland, oils from parking lots, etc.

What is the hydrologic cycle?

The total amount of water is the same, it is just recycled throughout the world.

How is water proportioned on earth? (e.g. how much freshwater vs saltwater; how much. is in glaciers, groundwater, etc.)

• Freshwater is a tiny percent of water on the planet

• Oceans make up 97.2% of the hydrosphere

• Glaciers are 2.15%, and that is freshwater

• Groundwater is 0.62%, which is the greatest quantity of liquid water

What factors affect a stream?

• gradient, or slope

• channel characteristics -shape, size, and roughness

• discharge

How do streams erode?

sediment rushing downstream, driven by high-speed waters volume, and slope cause the stream to deepen and widen overtime

In what directions do streams erode?

Streams can erode laterally, vertically, and toward the headwaters

What is the relationship between stream velocity and particle size?

Bigger particles slow down the stream as opposed to streams with less particles

How does a river change downstream?

It becomes wider, deeper, and faster as it gains water from tributaries

Where is the fastest flow in a stream?

Surface above the deepest water

Be able to label the parts of a meandering stream:

Meanders – curves in the stream

• Cutoff meanders – no longer attached to the stream

• Oxbow lakes – cutoff meanders filled with water

• Meander scar – cutoff meander not filled with water

Describe the different types of drainage patterns:

Dendritic - many tributaries connecting to a mainstream channel; resembles a tree; typical of flatter areas with softer material (easily eroded in any direction)

Radial - streams originate from one central location; typical of mountain or volcano tops

Rectangular - streams that meet at near right angles; typical of highly fractured rock areas

Trellis - tributaries that form parallel to one another; typical of areas confined by mountain ranges or ridges (streams are in the valleys) 

What are some ways we can control floods?

• artificial levees

• Flood-control dams

• Channelization

• Sound floodplain management (constructed wetlands, for example)

Be able to determine the recurrence interval and probability from a graph:

Explain the conditions that make material a good aquifer:

Needs to be a permeable layer, high porosity and high permeability

What material/rocks make good aquifers?

Sandstone, conglomerate, limestone, highly fractured igneous or metamorphic rock.

What material/rocks make good aquitards?

 Shale, unfractured igneous or metamorphic rock

Be able to label an unconfined aquifer, aquitard confined aquifer artesian well, and a recharge zone on an image:

Why is subsidence a huge concern?

Because once you draw water out of land, it will no longer hold as much as it did before. This causes flooding, sinkholes, and damage to infrastructure.

How have humans altered groundwater?

They have caused land to subsidise contaminated groundwater through agricultural and industrial activities, and treated it as a renewable resource even though it is not a renewable resource.

What is the Ogallala Aquifer?

It is one of the largest underground freshwater resources in the world!

What are the major concerns for the Ogallala Aquifer?

unsustainable depletion due to excessive agricultural pumping, which far exceeds the natural recharge rate

Why is the Ogallala Aquifer significant?

It provides water for 82% of the 2.3 million people in the High Plains area and irrigates over 30% of U.S. crops and livestock, transforming the region into an agricultural powerhouse.

How do caves form?

They form by dissolving rock beneath Earth’s surface, and are formed in the zone of saturation.

What features are found within caverns?

A: stalactites (hanging from the ceiling) and stalagmites (growing upward from the ground) - both of these formations are composed of dripstone

Chapter 9 Scripture

Ecclesiastes 1:7 - “All streams flow into the sea, yet the sea is never full. To the place the streams come from, there they return again.

Glacier

a thick mass of ice that forms over land from the compaction and recrystallization of snow and shows evidence of past or present flow.

Crevasse

form in brittle ice - very large fractures in the ice

Zone of accumulation

the area where a glacier forms

(material is being added to the glacier)

Zone of ablation

the area where there is a net loss due to melting

(also called the zone of wastage)

Plucking

lifting of rock blocks out of the ground

Rock Flour

(pulverized rock)

• makes glacial lakes look opaque or cloudy

Striations

• (grooves in the bedrock)

• basically like scratch marks that indicate the direction of ice flow.

• It is impossible for a piece of rock in the ice to leave a scratch perpendicular to, or any direction other than, the direction of ice flow.

Till

• material that is deposited directly by ice

• poorly sorted,

• loose sediment

Stratified drift

sediment deposited by the meltwater of a glacier

Fjord

• a glacial trough now filled with water

• forms when a glacier flows into a large lake or ocean

Horn

high point where cirques and arêtes meet