geology exam 4

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The evolution of tree roots may have helped cause a mass extinction about 350 million years ago. As roots decay they release phosphorus. If this phosphorus rapidly accumulated in the ocean, it could have caused massive algal blooms. Algal blooms remove oxygen from water, thus killing off lots of marine organisms if the oxygen levels get too low.

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Desert dust preserved in glaciers is used to study ancient climate. A recent Ohio State study examined dust in glaciers from Tibet. One of Clemson's geology faculty does similar research and has taken some undergrads to South America to do field work on dust deposits.

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Scientists are launching a new series of studies on subduction zones to better prepare for natural hazards associated with them. Many of Earth's strongest earthquakes and most active volcanoes are located along subduction zones.

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coal is not a hydrocarbon

rivers and streams

major agents of weathering and erosion

drainage basin

area that's going to drain into the river basin

channel

pathway where waters actively flow (v-shaped)

tributaries

smaller channels that eventually feed into larger channels

branching/dendritic tributaries

branching out

radial tributary

looks like streams are radiating out from central mountain point

rectangular tributaries

tributaries are about 90 degrees

levee

a wall of earth built to prevent a river from flooding its banks

floodplain

The area subject to flooding during a given number of years according to historical trends.

braided streams

consist of a series of intertwined channels that are overloaded with sediment; caused by variable discharge, large sediment supply, and easily erodible banks

channels

regulate water flow and solutes through membrane

steep elevation gradients

in steep elevations, channels are very straight
-lots of velocity = lots of erosion

meandering

wandering channel; looks like NASCAR turns (banks); migrate over time

oxbow lakes

crescent-shaped lakes formed in river valleys as a result of meandering streams

floods

An overflowing of a large amount of water beyond its normal confines, esp. over what is normally dry land

discharge calculation

discharge = velocity * area

recurrence interval

the average time between successive geologic events; probability = (1/int.)

mouth of river

the place where a river empties into a larger body of water

distributaries

a section of a stream that leaves the main flow

deltas

deposits of sand and soil at the mouth of a river form

Subsidence

the sinking of regions of the Earth's crust to lower elevations

50 liters per day

amount of water needed for a person to live comfortably

potability

A measure of how suitable water may be for drinking

fecal coliform count

# of coliform bacteria / 100 ml

chemical contamination

chemicals commonly added to water via infiltration and runoff; pesticides, fertilizers, pharmaceuticals

hydrology

Study of water

hydrologic cycle

the movement of water through the biosphere

oceans, glaciers, groundwater

largest sources of water

runoff

water that flows over the ground surface rather than soaking into the ground

infiltration

the process by which water on the ground surface enters the soil

porosity

The percentage of the total volume of a rock or sediment that consists of open spaces.

intergranular pores

the spaces between grains of sediment

fractures

to break

vugs

open spaces created by dissolution of some material
Ex: caves & caverns

sorting of porosity

well sorted = high porosity
poorly sorted = low porosity

cementation

The process in which minerals precipitate into pore spaces between sediment grains and bind sediments together to form rock.

permeability

Ability of rock or soil to allow water to flow through it

water table

The upper level of the saturated zone of groundwater

aquifer

A body of rock or sediment that stores groundwater and allows the flow of groundwater.

unconfined

an aquifer that intersects the surface

aquitard

A slab of impervious surface at the bottom of an aquifer that does not allow water to go through

confined

an aquifer surrounded by a layer of impermeable rock or clay that impedes water flow

artesian well

A well in which water rises because of pressure within the aquifer

perched aquifer

Localized zone of saturation above the main water table created by an underlying layer of impermeable material.

recharge

new water that enters the aquifer from the surface

discharge

An outflow of water from a stream, pipe, groundwater aquifer, or watershed; the opposite of recharge.

overdrafting

the process of extracting and using groundwater beyond what is replenished by the original water source

cone of depression

lowering of the water table around a pumping well

subsidence

the sinking of regions of the Earth's crust to lower elevations

desalinization

the removal of salt from ocean water

slowly

groundwater moves ______________

water distribution

states fight over this

love canal

toxic waste site in New York filled with drums of waste that leaked.

coastlines

the outline of a coast, especially with regard to its shape and appearance.

55%

this much of the population lives within 50 miles of a coastline

coasts

Where the land meets the sea

tides

the regular rise and fall of the ocean's surface influenced by the moon's gravity pulling on earth

tide height

- affected by how connected coastline and ocean are
- if open - tide range is very small
- if not in direct contact, tide range is large (low tide changes drastically)

wavelength

Horizontal distance between the crests or between the troughs of two adjacent waves

longshore current

a water current that travels near and parallel to the shoreline

longshore drift

The movement of water and sediment down a beach caused by waves coming in to shore at an angle

shoreline features

depends on tectonics, rock type, sea level fluctuations, and storm size

emergent coastline

Coastline that results from either a drop of sea level or an uplifting of the land

stacks

little steep rocky islands

terrraces

big flat step-like landforms

submergent coastlines

Produced by rising sea levels; area is sinking

spit

A beach formed by longshore drift that projects like a finger out into the water

barrier islands

low, narrow, sandy islands that form offshore from a coastline.

continental margin

a boundary between continental crust and oceanic crust

active continental margin

a continental margin that coincides with a plate boundary

passive continental margin

Margins that consist of a continental shelf, continental slope, and continental rise. They are not associated with plate boundaries and therefore experience little volcanism and few earthquakes.

continental shelf

A gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent

continental slope

a steep incline of the ocean floor leading down from the edge of the continental shelf

continental rise

the gently sloping surface at the base of the continental slope

coastal erosion

the loss of coastal land

zoning

build further inland

setback distance

How far back from the coast is it safe to begin construction

erosion lines

line along the coast marking where erosion will move the shoreline to in the future

e-lines

designates a zone of expected erosion.

barriers

weaken waves or keep sand in place

seawalls

walls built parallel to the coast to block waves before they hit the shore

groins

short, artificial walls built perpendicular to the shoreline to trap sand moved by longshore currents.

beach renourishment

the process of dumping sand from another location onto an eroding shoreline to create a new beach or to widen the existing beach

beach nourishment

dumping new sand onto eroding beaches to restore them

renewable energy

A resource that has a theoretically unlimited supply and is not depleted when used by humans.

nonrenewable energy

A source of energy that is a finite supply capable of being exhausted.

fossil fuels

Coal, oil, natural gas, and other fuels that are ancient remains of plants and animals; 81% of energy consumption in US and globally

reserve

in resource management, the known quantity of a resource that can be economically recovered

resource

A substance in the environment that is useful to people, is economically and technologically feasible to access, and is socially acceptable to use.

Fossil Fuel Advantages

Cheap & Abundant
Technologically well developed
Infrastructure is built to run off of them

fossil fuel disadvantages

Nonrenewable
Increasing costs
Deposits not evenly distributed
Environmental Damage

hydrocarbons

combustible H-C carbons; requires area of high biological productivity and relatively low oxygen in waters/sediments

methane

natural gas, growing resource, burns cleaner than other fossil fuels, cheaper than oil; safety issues, contributes to carbon buildup

oil

66% is in Middle East, 22% in Saudi Arabia

7.2

USA used ______ billion barrels in 2016

fracking

hydraulic fracturing