Study Guide, Everything After Spring Break - Earth History and Resources | 012 003 | Study notes Earth Sciences

Deserts

Desert: an area where annual precipitation is less than potential water loss by evaporation.

Steppe: semi-arid borders of deserts.

*Dry regions (steppes and deserts) cover 30% of Earth’s land surface (~42 million km2 )

Types of deserts

oHot and Dry: warm all year (very hot in summer). Very low rainfall that often evaporates in air

oSemiarid: summers long and dry, winters have low precipitation, rainfall very low but

concentrated when it does come.

oCoastal: semi-long warm summers, cool winters. Rainfall low and in short bursts.

oCold: short warm summers, long cold winters with snow. High precipitation in winter.

Where deserts form

oLow-latitude: 20-30 degrees N and S. In high pressure zones.

oMid-latitude: areas by mountains

oRain shadows: winds move precipitation to one side of mountain leaving arid desert on other

oContinental interior: inlands of large land masses.

*Weathering is mostly mechanical instead of chemical

*Most desert erosion is the result of running water

*Rain rare but usually very heavy resulting in flash floods and a lot of erosion

*Rivers usually form outside of desert in mountains and pass through.

Groundwater: water table usually very deep forming oasis where it intersects the surface

*Deserts have poor drainage systems; most runoff does not reach sea causing erosion

Landscape evolution

oEarly: often driven by block faulting and tectonic uplift of mountains. Running water and

streams also contribute

oLate: mountains lower and basins fill with sediment.

Alluvial fans: form at canyon mouth

Playa lakes: form in flat central area of un drained desert basins

Bajada: an apron of sediment along a mount front

Inselbergs: isolated mountain remnants

Wind

oTransport: moves particles and can result in dust and sand storms

Suspended load: fine particles transported within the air

Saltation: transport of particles through a series of bounces

Bed load: particles moved along the ground surface by wind (creep)

oErosion:

Deflation: wind lifts loose sediment and leaves behind larger grains

Blowout dunes: depression excavated by wind

Yardangs: wind sculpted ridges

Ventifacts: stones with flat ridges

oDeposits: form dunes and loess

Loess: wind silt accumulates, extremely fertile farm land

Dunes: hill or ridge of sand

Transverse: series of long rides perpendicular to wind

Longitudal: parallel with wind

Barchans: shaped like crescent with tips pointing downwind

Parabolic: tips point into with instead of with wind

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Deserts  Desert: an area where annual precipitation is less than potential water loss by evaporation.  Steppe: semi-arid borders of deserts. *Dry regions (steppes and deserts) cover 30% of Earth’s land surface (~42 million km^2 )  Types of deserts o Hot and Dry: warm all year (very hot in summer). Very low rainfall that often evaporates in air o Semiarid: summers long and dry, winters have low precipitation, rainfall very low but concentrated when it does come. o Coastal: semi-long warm summers, cool winters. Rainfall low and in short bursts. o Cold: short warm summers, long cold winters with snow. High precipitation in winter.  Where deserts form o Low-latitude: 20-30 degrees N and S. In high pressure zones. o Mid-latitude: areas by mountains o Rain shadows: winds move precipitation to one side of mountain leaving arid desert on other o Continental interior: inlands of large land masses. *Weathering is mostly mechanical instead of chemical *Most desert erosion is the result of running water *Rain rare but usually very heavy resulting in flash floods and a lot of erosion *Rivers usually form outside of desert in mountains and pass through.  Groundwater: water table usually very deep forming oasis where it intersects the surface *Deserts have poor drainage systems; most runoff does not reach sea causing erosion  Landscape evolution o Early: often driven by block faulting and tectonic uplift of mountains. Running water and streams also contribute o Late: mountains lower and basins fill with sediment.  Alluvial fans: form at canyon mouth  Playa lakes: form in flat central area of un drained desert basins  Bajada: an apron of sediment along a mount front  Inselbergs: isolated mountain remnants  Wind o Transport: moves particles and can result in dust and sand storms  Suspended load: fine particles transported within the air  Saltation: transport of particles through a series of bounces  Bed load: particles moved along the ground surface by wind (creep) o Erosion:  Deflation: wind lifts loose sediment and leaves behind larger grains  Blowout dunes: depression excavated by wind  Yardangs: wind sculpted ridges  Ventifacts: stones with flat ridges o Deposits: form dunes and loess  Loess: wind silt accumulates, extremely fertile farm land  Dunes: hill or ridge of sand  Transverse: series of long rides perpendicular to wind  Longitudal: parallel with wind  Barchans: shaped like crescent with tips pointing downwind  Parabolic: tips point into with instead of with wind

Shorelines  Shoreline: line that marks the contact between land and sea (constantly moving)  Coastline: coast’s seaward edge; landward limit of the effect of the highest storm  Wind-generated waves: provide most of the energy that shapes and modifies coastal zones  Crest: high point of a wave  Trough: low point between two waves  Wave height: distance between trough and crest  Wave length: horizontal distance between two crests  Formation of waves: wind is primary factory. Energy transfers from wind to water through pressure and friction  Oscillation waves: occur in open water, water travels in circular orbits. Rock back and forth  Effect of Shallowing: water moves increasingly elliptical towards floor. Crest heights increase and wave length gets shorter. Turbulent water advances up shore and forms surf.  Translation Waves: turbulent advance of water created by breaking waves in shallows  Shore Zones o Offshore: seaward of where waves break at low tide o Nearshore: zone between where waves break at low tide to low-tide level o Foreshore: area between low-tide and coastline; most active area, typically wet o Backshore: area inland of foreshore, affected by storm waves and high tides. Wind effects  Wind Erosion o Wave impact and pressure erode land o Abrasion from rock fragments erode as well  Beaches: waves act to accumulated sediment along land o Form from breaking waves moving sediment.  Shoreline features: vary by rockiness of shore, currents, wave intensity, and whether the coast is stable, sinking, or rising  Terrace: flat area exposed during low tide composed of fine grained sediment  Berm: ridge of poorly sorted sediment from waves at upper limit of high tide  Dunes: hill of fine grained sand relative to shore. Can go for miles or be stopped by cliffs  Emergent coast: when coast rises or sea level drops. Cliffs retreat while beach extends at base o Jagged cliffs, wave-cut notch or platforms. Can form sea caves or sea stacks.  Submergent coast: sea level rise or land subsides. o River valleys become estuaries (drowned river mouths), hills become islands. Highly irregular shoreline  Factors of erosion and deposition: degree and type of tectonic activity; topography and composition of land; configuration of coastline and nearshore; prevailing wind and weather patterns; proximity to rivers  Wave Refraction: waves slow as they enter shallow waters o Concentrated against sides and end of headlands, forms beaches and irregular coastlines. Erosion will eventually straighten out coastline.  Oblique Waves: flow parallel with coast instead of perpendicular. Cause current to flow parallel making longshore current.  Beach drift: oblique waves and longshore current cause sediment to move along beach in zigzag pattern  Baymouth Bar: a sand bar that completely crosses a bay  Tombolo: a ridge of sand that connects an island to the mainland or other island  Barrier Island: low sand ridges formed parallel to coast  Shoreline stabilization: man-made structures that prevent erosion o Sea wall: parallel to shore and close to beach, stops waves from reaching shoreline o Breakwater: parallel to shore: protects from large breaking waves o Groin: short wall built at a right angle to trap moving sand o Jetty: pair of structures built to protect harbors against storm waves and deposition

 Composition: created by layers of gases surrounding planet, retained by gravity. Mainly nitrogen (78%) and Oxygen (21%)  Origin: gases were trapped from volcanic eruptions. Ancient atmosphere consisted of water vapor and carbon dioxide. Without atmosphere Earth would be 60 degrees cooler.  Oceans: started when water vapor accumulated producing precipitation. Rain turned into runoff into large basins producing oceans  Hydrologic Cycles: runoff and groundwater dissolved salts and carried into ocean, water moved from oceans to atmosphere by precipitation and salt concentrated in oceans.  Atmospheric Layers: denser gases sink, 90% in troposphere, no distinct upper limit. o Layers (top to bottom): Exosphere (600km), Thermosphere (90km), Mesosphere (50km), Stratosphere (10km), Troposphere (where we are, ground level)  Ozone: layer within stratosphere with high concentration of ozone molecules, absorbs UV, thickness varies from year to year and is thinner at Poles.  Temp of Atmosphere: Troposphere cools with altitude, ozone heats upper stratosphere, mesosphere cools with altitude. Uppermost layer is coldest place on earth. o Thermosphere and Exosphere: oxygen molecules absorb solar radiation, temp increases with altitude until gas is too thin to have effect o Auroras: solar winds drive charged particles into upper atmosphere, colorful lights. o Troposphere: convections moves air here, air parcels displace others.  Coastal Breezes: wind direction changes from day to night because of temp differences o Sea breeze: during day, air moves from sea to land o Land breeze: during night, air moves from land to sea because of water’s retention of heat  Atmospheric Convection: moving air masses create pressure zone (low where they begin, high where they’re going). Air masses create wind when moving from high to low pressure zones o Barometric pressure: force per unit area exerted by atmosphere on surface beneath or within it.  Adiobatic Changes: gas changes pressures so temp changes o Heating: air sinks, pressure increases and forces parcel volume to contract o Cooling: air rises, pressure decrease and parcels expand  Cloud Formation: rising air is moist; water vapor condenses to water droplets as parcels cool. o Low pressure zone: converging winds to rising air mass, cloud formation and precipitation o High pressure zone: diverging winds from sinking air, clear and cool weather  Cyclones: low atmospheric pressure produces inward spiraling wind.  Hurricanes: tropical cyclones, sustained near-surface winds exceed 73 mph  Tornadoes: small cyclones with strong winds, tube like condensations funnel from rotation cloud.  Weather fronts: transition zone between air masses of different densities. Extend horizontally and vertically and are marked by cloud formation.  Clouds: visible mass of condense water or ice suspended in atmosphere o Types are defined by altitude and whether they are layered or convective o Formed by orographic uplift, most winds forced up by hills, cool and precipitate on wind side o Convectional lifting: air mass is warmed and rises, then expands and cools higher, clouds. o Frontal lifting: convergence of air masses; warmer, moister air mass will override cooler o Radiative cooling: air above ground cools and turns to fog after sun sets.  Precipitation: condensation of atmosphere water vapor that falls to surface  Thunderstorms: form when an air mass with a lot of condensation is forced upward rapidly in an unstable atmosphere, where temperature drops.  Lighting: electricity resulting from differently charged particles in air. Typical of thunderstorms  Global wind patterns: result from temp-driven convection, adiabatic effects, coriolis effect, and seasonal shifts

o Convection: circulates air by the unequal warming at different latitudes o Variation in moisture levels: results from evaporation and condensation. Patters cause cool dry air to sink. o Coriolis: deflects air currents to right in northern hemisphere and left in southern. o Seasonal changes: solar heating of Earth’s surface affects distribution of high and low pressure areas.  Seasonal Variations: result from variation in solar radiation reaching ground. The bariation happens when the tilt of earth’s axis rotates. One part of planet gets more sun as result  Mid-latitude seasons: seasonal latitude marked by changes in earth’s axis  Equatorial seasons: amount of precipitation often varies more than temp resulting in distinct seasons  Monsoon: heavy rainy season that lasts for several months with lasting climatic effects *Temperature varies more in continental interiors than on coasts

 Distribution of Fossils: may be found in sedimentary rock but most common in rocks formed in environments with rapid deposition and minimal diagenesis. (review map)  Process: first something dies, then it is buried, then diagenesis takes over. Remains must survive long enough to be discovered  Enemies of preservation: destructive scavenging, transport of organism by wind or water, or slowed delayed deposition of sediment (oxygen = decay).  Deposition environment: an organism that dies in a place where it can be immediately buried is more likely to fossilize  Autochthonous: organisms preserved in their original position  Allochthonos: fossil assemblages preserving organisms that were transported prior to deposition  Bioturbation: organisms burrowing through sediments.  Dissolution: hard parts can and will dissolve from certain pH levels or other chemicals  Diagenesis: physical and chemical changes during lithification of sediment  Metamorphosis: folding or heating of fossiliferious rocks  Exposure: rock must be exposed or discovered to be studied (erosion, uplift, drilling, etc.)  Modes of Preservation: o Body Fossil: preserved remnants of an organism o Ichnofossil: tracks, burrows, or other indications that living organisms were present  Trackway: series of tracks or footprints left by a single organism. Can provide info on tissue, movement, and behavior of organism.  Coprolites: fossilized feces can show diet of species.  Burrows: shows info on behavior, preserved when burrow is flooded and filled with sediment  Hard vs. soft parts: soft tissue is less likely to be preserved than bone, shell, wood, etc.  Permineralization: pore spaces in hard parts are filled by minerals from ground water  Replacement: pore spaces and other parts are completely replaced with minerals (mostly wood) o Petrifaction: Silica binds to cellulose and crystallizes and preserves it.  Compression: 2D, often distorted. Physically compressed organism by overlying sediments  Impression: organism is lost but imprint is left in sediment, details preserved o Molds and Cast: mold is the impression, it is a mirror image. A cast fills the mold and leaves a replica of the organism  Lagerstatte: extraordinary fossil deposit o Conservation: a deposit with preservation of morphology (soft parts that are usually not found) o Concentration: exceptional taxonomic preservation, due to high preservation rates.  Resin Fossils: mode of fossilization that often preserves morphological detail. Usually plants or insects are trapped in tree sap or amber and are completely reserved in their original state.  Taphonomy: study of all processes that happen between death of an organism and fossilization  Preservation rates: used to asses completeness of a fossil record  Taphonomic Filters: o Number of parts: the more an organism has, the more are likely to get lost o Population Abundance: the more of an organism that existed, the more likely it is to be fossilized  Live-dead study: a census of the organisms living in an ecosystem is compared to the species preserved in the sediment. Life assemblage to death assemblage. Used to find preservation rates *Study slides on page 7 for percentages of organisms fossilized in a certain community  Spatial sampling: finding the percent. Most fossil assemblages are part local, part regional Biodiversity and Extinction

 Taxonomy: the classification, identification, and the naming of organisms. Started by Carl von Linne o Linnean Taxonomy: a method of classifying living things in a ranked hierarchy. Similar organisms are a species, similar species are a genus, and similar genus is a family. o Binomial nomenclature: species get a two part name. Genus name and species name ( Homo sapien ). First name capitalized, second not. Always italicized or underlined.  Describing species: scientists write a summary of new taxon’s characteristics such as traits it shares and those that make it unique.  Peer-Review system: to publish, a scientist sends work to an appropriate journal, 2-4 other scientists review the topic, and author accepts/rejects changes.  Type Specimen: a specimen identified as the example of the taxon illustrated by the formal description  Taxonomic Relationships: species with common ancestors and similar traits are categorized together  Phylogeny: relationship among species. Closely related species are branched together while others are branched apart.  Stratigraphic Range: the duration of time between the oldest occurrence of a fossil species (origin) and the youngest occurrence of that species (extinction). Basically duration of a species  Phanerozoic marine animal biodiversity: graph on page 5, slide 4  Diversity turnover: average stratigraphic range is 5-20 million years. About 99% of all species that have ever lived on Earth are now extinct  Origin of Atmosphere: gases were trapped from volcanic eruptions. Ancient atmosphere consisted of water vapor and carbon dioxide. Without atmosphere Earth would be 60 degrees cooler.  Precambrian: spans first 4 billion years of Earth’s history. Hadean (4600 to 4000mya), Archean (4000- 2500mya), and Proterozoic(2500 to 542mya) o Physical and Chemical Weathering: out gassing produced acidic conditions (accelerated chemical weathering). Precipitation and runoff increases physical weathering, sediment deposits and salinity  Precambrian Oxygen: photosynthetic organisms started producing oxygen about 3.5bya. o Banded Iron Formations: early iron oxide deposits accumulated on the seafloor as alternating layers of iron-rich rocks and chert. o Stromatolites: distinctively layered mounds of calcium carbonate and filamentous bacteria o Red Beds: evidence of chemical oxidation (especially iron) in continental sediments  Great Oxidation Event: 2.4bya excess oxygen released in atmosphere, became toxic to dominate organisms (anaerobic bacteria), and led to ecological crisis then metabolic revolution.  Ozone in Atmosphere: harmful to most cells: ocean water shields marine organisms. Formed in UV radiation. Became protective layer allowing organisms out of Deep Ocean.  Prokaryotes: organisms lacking nucleus or other membrane-bound organelles. Mostly unicellular.  Eukaryotes: cell that engulfs another cell. Membrane bound organisms o Grypannia: multicellular eukaryote. o Bangiomorpha: sexual eukaryote. Intercalary pattern of cell division.  Vendian biota: oldest fossil evidence of multicellular organisms. (Algae, lichens, etc.)  Doushantuo Microfossils: from late Proterozoic marine rocks in southern china. Appear to preserve embryos of ancient organisms.  Embryos: go through a rapid series of cell divisions, without cell growth or cell differentiation cleavage.  Burgess Shale: rocks that preserve a 500ma ecosystem from the sea floor.  Paleozoic invasion of land: animals and plants evolved to protect against solar radiation, dehydration, and breathing oxygen. Insects and plants eventually moved to shore. Lobe-finned fishes adapted and became first amphibians.  Iowa Carboniferous. About 300mya Iowa was warm and humid. Extensive swamps and tree ferns. Swamp plants became coal deposits over time after compression  Mass Extinctions: an event when there is a massive decline of life and biodiversity. 5 in Phanerozoic.  Causes of Cretaceous/Tertiary Extinctions: probably asteroid impact accompanied by volcanic eruptions, climate change, and wildfires.

Energy Resources  Nonrenewable: form or accumulate over millions of years, so quantities are considered fixed (Coal, iron, natural gas)  Renewable: virtually inexhaustible or can be replenished relatively quickly (sun, wind, tides)  Consumption: U.S. energy consumption has increased over last 100 years. Usage of different resources has also changed. Review graph page 1, slide 5 and map slide 6  Fossil Fuel: general term for any hydrocarbon (organic material) that may be used as fuel (coal, natural gas, bitumen from oil sand and oil shale)  Coal: readily combustible sedimentary rock formed by compaction of plants over millions of years o Single most used energy resource world-wide o Limited resource, mining can cause major environmental damage and air pollution  Oil and Natural gas: consist of hydrocarbons from marine plants and animals. Takes millions of years. Must accumulate between cap rock and reservoir rock. o Cap rock: a rock impermeable to oil and gas o Reservoir rock: a porous and permeable rock.  Oil Trap: A geologic environment that allows significant amounts of oil and natural gas to accumulate underground o Anticlinal trap: rising oil and gas collect at a fold apex in an up-arched series of sedimentary strata o Fault Trap: upward migration of oil and gas is trapped where displaced strata bring a dipping reservoir rock opposite an impermeable bed. o Salt Dome: Rising oil and gas accumulate in deformed, upturned sandstone beds adjacent to salt dome. o Stratigraphic trap: trapped by an original sedimentary structure: a sloping bed of reservoir rock thins to point of disappearance (pinches out)  Drilling: Cap rock is punctured. Oil and natural gas under pressure migrate from pore spaces to surface. Stored in tanks  Oil Sands: a mixture of clay and sand combined with water and bitumen. Several substantial deposits exists but major environmental drawbacks and expenses exist when drilling  Oil Shales: fine-grained sedimentary rock with enough organic material to yield oil or gas. Currently too expensive with current technology  Gas Hydrates: a solid form of water that contains large amounts of methane within its ice-like crystals.  Hydraulic Fracturing (Fracking) process for artificially increasing a reservoir rock’s permeability to get oil and gas. o Fluid is pumped into rock causing it to fracture. High pressure forces gas out o Large amounts exist but can contaminate water and cause earthquakes.  Biofuels: fuel derived from biomass (recently living organisms). Renewable but produce greenhouse gases.  BioEthanol: most common type of biofuel. Obtained from starch or sugar found in many crops.  Switchgrass: a hardy, perennial grass native to North American prairies, considered good candidate for biofuel. Rapid growth and in large quantities. Doesn’t need to be replanted.  Wind Energy: wind pushes objects creating kinetic energy. Windmills make this kinetic energy into electricity. Iowa is 2nd^ largest producer of wind energy next to Texas.

Mineral Resources:  Mineral Resources: naturally occurring useful and essential minerals from Earth’s crust, ultimately available commercially according to value (iron ore, lead, tin, copper, zinc, mercury, bauxite) o Reserves: already identified deposits of minerals that can be extracted profitable o Known-deposits: exists but are not economically or technologically recoverable yet.  Ore: rock containing useful metallic minerals that make it valuable for mining.  Magmatic Segregation: local concentration of minerals formed during cooling and crystallization of magma o Separation of heavy minerals that crystallize early o Enrichment of rare elements in the residual melt  Diamonds: form of carbon created at great depths under high pressure, once crystallized diamonds are carried up through conduits within ultramafic rock called kimberlite pipes.  Hydrothermal deposits: solutions of hot, metal-rich fluids move through rock, depositing metals (usually as sulfides) as the fluid cools. Among best known and important minerals o Vein deposits: solution moves along fractures, cools, and precipitates within cracks o Disseminated deposit: ores precipitated as minute masses throughout entire rock mass o Surface deposit: where magma is near surface, dissolved metals precipitate when water cools in air.  Metamorphic ore deposits: many of important deposits are produced by contact metamorphism (Sphalerite, Galena, Chalcopyrite) Produced by Contact metamorphism and regional metamorphism.  Secondary Enrichment: concentration of scattered, minor amounts of metals by weathering processes. o Chemical weathering and water percolation remove undesirable elements from decomposing rock o Desirable elements found near surface are carried to lower zones, and concentrated. o Examples: copper, silver, bauxite  Bauxite: principal ore of aluminum, formed by secondary enrichment in rainy climates.  Placer Deposits: formed when heavy minerals are mechanically concentrated by currents, most commonly streams and waves; typically heavy and durable minerals. (gold, tin, platinum, diamonds)  Nonmetallic Mineral Resources: o Building materials:  Natural aggregates (crushed stone, sand, gravel)  Gypsum (plaster and wallboard)  Clay (tile, bricks, and cement o Industrial Minerals:  Fertilizers (nitrate, phosphate, and potassium compounds)  Sulfur (sulfuric acid to manufacture phosphate fertilizers)  Salt (used in chemical industry, softening residential water, and keeping street ice-free)

Earth’s Systems: Geosphere, Hydrosphere, Atmosphere, Biosphere Answers to recent clicker questions (should be recognizable on test)

Earth’s primitive atmosphere: Water Vapor and Carbon Dioxide
Earth’s atmosphere today: Nitrogen and Oxygen
Banded iron formation and red beds
Birds: closest ancestors to dinosaurs
Cap Rock and Reservoir Rock: needed to make oil and natural gas
Swamp plants: primary source of coal

Study Guide, Everything After Spring Break - Earth History and Resources | 012 003, Study notes of Earth Sciences

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