Earth Science Final Review

Who was Alfred Wegner?

German meteorologist who proposed the idea of continental drift and Pangaea

What was Wegner’s evidence for continental drift?

• The fit of the continents

• The distribution of climate belts

• Distribution of fossils

• Matching geological units

What was the problem with Wegner’s theory about continental drift?

He didn’t have evidence to prove the the continents moved

What is the asthenosphere?

The mantle just below the lithosphere that can flow plastically

What is the lithosphere?

The rigid crust and upper mantle of the Earth

What are the similarities and differences between the lithosphere and the asthenosphere?

The main difference is that the lithosphere is cooler than the asthenosphere. They have the same composition but the asthenosphere is at a temperature where it can flow.

What is oceanic crust? Where does it come from?

Oceanic crust is mainly made of basalt. Oceanic crust is developed at divergent plate boundaries.

What are the three types of subduction?

• Oceanic - oceanic

• Oceanic - continental

• contiental - contiental

What are the three types of plate boundaries?

• Convergent

• Transform

• Divergent

What happens in a convergent plate boundary?

This plate boundary is when tectonic plates move towards each other. There is always a plate that goes below and the process of the plate being forced down is known as subduction.

What happens in a divergent plate boundary?

This plate boundary is where tectonic plates move away from each other, expanding a mid-ocean ridge where material from the asthenosphere comes up to the surface.

What happens in a transform plate boundary?

In this plate boundary, plates slide past one another. No new plate is formed and no plate is consumed.

What is source rock? How is it formed?

Source rock is organic shale that contains the materials from which hydrocarbons can form. It is formed when plankton and clay floating in water sink and accumulate into a layer on the ocean floor. Over time, more sediment accumulate over this layer and compress it down. This layer is then transformed into organic shale with kerogen in it — creating source rock.

What is a reservoir rock and how is it formed?

Reservoir rock is a rock with high permeability and porosity where oil and gas migrate upwards to. It is formed as the oil and gas leave the source rock and continue to travel upwards until it is stopped by a seal rock, making a trap beneath the seal rock in the reservoir rock.

What is a trap and how is it formed?

A trap is a space between the reservoir rock and the seal rock where oil and gas sit until it is extracted. It is formed when oil and gas can no longer travel upwards because they run into a rock that is not permeable and has low porosity.

What are the types of hydrocarbon traps?

• Anticline trap - oil and gas rise to the top of the fold

• Fault trap - Oil and gas collect in tilted strata adjacent to the fault

• Salt-dome trap - Oil and gas collect in strata on the flanks of a salt dome.

• Stratigraphic trap - Oil and gas collect where the reservoir-rock layer pinches out

Where does petroleum come from?

Petroleum is formed from the remains of plants and animals (mainly animal tissue in the form of plankton) that have been covered by layers of sand, silt, and rock.

What is the origin of coal?

Coal is formed from organic materials (mainly woody plants) that die and fall into water with low oxygen content. Decay of the plants happens very slowly so it transformed into peat then coal and it gets buried.

What are the grades of coal from lowest to highest?

• Lignite coal

• Bituminous coal

• Anthracite

List the types of fuels on highest energy density to lowest energy density?

• Uranium-235

• Gasoline

• Propane

• Coal

• Wood

• Gunpowder

• Lithium battery

• Lead-acid battery

What are conventional petroleum resources?

Conventional petroleum resources are things that can be pumped with relative ease by using things like oil rigs to puncture and pump reservoir rock

What are unconventional petroleum resources?

Unconventional petroleum resources are places were oil cannot be easily pumped out of the ground. Thins like oil shale, tight oil/gas, and tar sands.

What is hydrofracturing?

In hydrofracturing, fluid is pumped under high pressure into impermeable rocks to open existing cracks and to form new cracks that will allow more oil/gas to enter pipes and flow.

List the different types of mass wasting from slowest to fastest

• Creep and Solifluction

• Slumping

• Mudflows/Mudslides and Lahars

• Debris Flow

• Rockslides/Rockfalls and Avalanches

What are some commonalities with causes of mass wasting?

• Lack of vegetation

• Increased water content/pressure

• Weathering

What are things that can be done to prevent mass wasting?

• Revegetation

• Regrading

• Reducing subsurface water

• Preventing undercutting

• Constructing safety features

• Controlled blasting of unstable slopes

What is angle of repose?

This is the steepest angle material can maintain without collapsing. It depends on the shape and size of the grains in the pile.

How do turbidity currents occur?

These occur when moving sediment disperses in water to yield a turbulent cloud of suspended sediment that rushes downslope like an underwater avalanche.

What is a drainage basin?

This is the overall region drained by a given drainage network.

What is a drainage divide?

This is the boundary between drainage basins.

What are oxbow lakes?

These used to be meanders of a stream that were cut off to be their own lake.

Name the types of drainage networks (5)

• Dendritic

• Trellis

• Radial

• Parallel

• Rectangular

Describe dendritic drainage

This drainage network has a tree-like pattern as water flows downslope

Describe trellis drainage

this drainage network has valley tributaries join into a trunk stream that cuts across ridges

Describe radial drainage

this drainage network radiates out from a central high point

Describe parallel drainage

This drainage network has streams that trend parallel between ridges

Describe rectangular drainage

This drainage network follows preexisting cracks or joints.

What are the three ways streams transport sediment? Describe them.

• Dissolved load - dissolved ions

• Suspended load - tiny grains that swirl along without settling

• Bed load - larger clasts that slide or roll along the streambed

Compare permanent streams and ephemeral streams

Permanent streams are those that flow year-round and the bed of the stream lies below the water table.

Ephemeral streams only flow for part of the year and the channel of the stream lies above the water table.

Compare alluvial fans and deltas

An alluvial fan is a wedge of alluvial sediment where a stream exits a narrow canyon onto a plain.

A delta is a deposit of alluvial sediment formed where a stream enters a standing body of water.

What is alluvium?

Stream deposits

Compare aquifers with aquitards.

Aquifers are porous rocks or sediment that serve as reservoirs for groundwater. They must be permeable so that ground water can migrate to wells. (sandstone)

Aquitards are sediments or rocks with relatively low permeability (anything with a lot of clay - shale)

Define and compare porosity and permeability

Porosity is the total volume of open space within a material; specified as a percentage.

Permeability is the ability for water to migrate through pore spaces.

How doe sinkholes form?

Sinkholes are formed when the roof of a cave collapses. If there are many sinkholes in an area (due to lots of limestone) karst landscapes can form.

What are the main minerals dissolved in seawater?

Sodium and chloride

What is thermocline?

This is the boundary between warm surface waters and cold deeper waters

What is pycnocline?

This is the region where density varies most between surface density and deeper-water density.

What is halocline?

This is the boundary between surface and deep-water salinity.

What are the two layers of ocean currents?

Surface currents (100-400m) and deep-sea currents.

What is the average seawater salinity?

3.5%

What part of the earth tends to have seawater with higher salinity? Why?

Closer to the equator because there is more evaporation near the equator so the remaining water has higher salinity.

What part of the earth tends to have seawater with less salinity? Why?

Salinity is lower near the poles. This is because there is lots of ice and when it melts it dilutes the water.

What is the term for surface currents? What is the difference between them in the Northern and Southern Hemispheres?

They are known as gyres. They flow clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

What are dead zones? How do they occur

Overnutrients from fertilizer runoff leads to too much algae growth and the death of other plants in the area

What three oceanic zones are based on distance from shore? (Closest to farthest)

• Littoral

• Neritic

  • Oceanic

What are the two oceanic zones based on depth? (highest to lowest)

• Pelagic

• Benthic

What two zones are based on light penetration? (highest to lowest)

• Photic

• Aphotic

How are dead zones formed?

These are formed when decomposition of algal blooms removes oxygen.

What is uniformitarianism?

This states that the physical processes operating in the modern world also operated in the past.

What is relative dating?

This is dating rocks by comparing the ages of the rock above and below it.

What is absolute dating?

This is finding the age of a rock by using the rocks physical properties.

What are the 5 principles used to determine relative age?

• Original horizontality

• Superposition

• Cross-cutting relations

• Baked contacts

• Inclusions

What is original horizontality?

This states that layers of sediment are horizontal when they are first deposited and that can be assumed to be their original orientation.

What is superposition?

This states that if rock layers are laid down horizontally and undisturbed, the layers that are at the bottom and the younger layers are at the top.

What is cross-cutting relations?

This states that if one geologic feature cuts across another, the feature that has been cut is older.

What are baked contacts?

If there is an igneous intrusion baked into the wall rock, the rock that has been baked must be older than the intrusion

What does it mean if a rock has an inclusion?

If a rock contains an inclusion, the inclusion must be older than the rock that contains the inclusion.

What is the widely accepted age of Earth?

4.5/4.6 billion years old

What is isotopic dating and how does it work?

This is a technique for calculating numerical ages using the ratios of radioactive elements to their decay products. (parent isotopes to daughter isotopes) For each half-life that has passed, the ratio between the two changes.

What is a disconformity?

This is where the sedimentary beds above and below the unconformity are parallel, but the contact between them represents a hiatus. (both sedimentary rock layers but there is a missing piece in the time line)

What is a nonconformity?

This is where younger sedimentary rocks are overlying older igneous or metamorphic rocks.

What is an angular unconformity?

This is when rocks below are tilted at an angle to the younger overlying rocks.

What is the Keeling curve?

the graph measuring the increasing concentration of atmospheric CO2. (since 1955)

How does solar insolation affect climate?

This makes the climate vary with latitude because the amount of solar energy absorbed at the surface varies with latitudes. (Light shining directly at 90 degrees is more intense but affects a smaller area compared to light shining at a 50 degree angle is less intense but affects a larger area.)

Why are ice cores significant?

These reveal the atmospheric composition of the past with the ancient air trapped inside. They can also contain other materials that provide information about the climate.

Why does the Earth have periodic climate swings?

The combination of the axis’ procession, the tilt of the Earth, and the shape of the Earth’s orbit all combine to either increase or decrease the amount of sunlight and therefore the temperature at the Earth’s surface. (This varies over thousands of years)

When was the last ice age?

Around 8,000 B.C.

How do volcanoes impact the climate?

Ash found in the atmosphere from volcanic irruptions cools the area for a time but don’t contribute to the climate change significantly compared to things like human-made emissions.

What are sinks and what do they have to do with carbon emissions?

Sinks are things that uptake the carbon and take it out of the atmosphere (plants/forests and the ocean)

Where does most of the warming on Earth take place? Why?

Most of the warming is happening in the northern hemisphere (more like Canada than the US). This is mostly due to the fact that most of the developing world happens in the north hemisphere.

What are the three things needed for something to be planet?

• If it orbits the sun

• It is spherical

• it has cleared its orbit of other objects

What are the main differences between the terrestrial planets and the giant planets?

The terrestrial planets and the giant planets are separated by the astroid belt. The giant planets are all gas planets whereas the terrestrial planets are solid.

What is the astroid belt?

This is the group of asteroids that separate the terrestrial planets from the gas giants.

Why are there so few impact craters on Earth and why are there many on the Moon?

There are so few of these on Earth because it has an atmosphere that breaks apart meteors and because Earth’s surface is always changing so they aren’t visible (sedimentation and plate tectonics recycle the area). There are many of these on the Moon because the Moon doesn’t have an atmosphere and no plate tectonics to remove them.

What is the most widely accepted hypothesis for the formation of the moon?

Most believe that it was formed after a large impact on the Earth by a Mars-sized protoplanet that blasted debris into orbit. The material formed a ring around Earth and later formed together into the Moon.

Where is the biggest volcano in the solar system found?

This is found on Mars