ESC 240 Midterm 1

Urey Equation

CaSiO3 + CO2 < - > SiO2 + CaCO3

Uniformitarianism

The present is the key to the past

Hadean (Ma)

4000-4600Ma

Archean (Ma)

4000-2500Ma

Proterozoic (Ma)

2500-541Ma

Phanerozoic (Ma)

541-0Ma

Ernest Rutherford

Invented isotopic dating by calculating the age of a rock by measuring its uranium content

Absolute

based on isotopic dating

Relative

based on fossils

Alfred Wegener

meteorologist that first proposed continental drift in 1912

Harry Hess

hypothesized seafloor spreading

Marie Tharp

had a large role in mapping the world’s ocean floor

Continental crust is ___ dense than oceanic crust

less

Ocean Continent Convergence

Oceanic lithosphere is subducted and a volcanic mountain belt forms at the continental margin

Continent Continent Convergence

crust crumples and thickens, creating high mountains and a wide plateau

Continental Transform Fault

Plates slip horizontally past eachother (ex San Andreas)

Paleoecology

study of past species distrubution and environmental factors

Ecological niche

how a species relates to its environment

Ecosystem

the combination of a community of organisms and the physical environment

Biodiversity is important for ____ ____

ecosystem recovery

Biogeography

Distrubution and abundance of organisms on a broad geographic scale

Composition of the Atmosphere

78% Nitrogen, 21% Oxygen, 1% Argon, trace gases (ozone, water CO2, methane)

Net transportation of air from the equator ____ to the poles ____

(rises) (sinks)

Ocean reflects ___% solar radiation

6-10

Forest reflects ___% solar radiation

5-30

Ice and snow reflect ___% solar radiation

45-95%

The ITCZ

inter tropical convergence zone

Jagged margin leaves

Cooler temperature

Smooth margin leaves

Warmer temperature

Waves

high energy transport, associated with sand deposits

Tidal Flats

barren regions along coastal margins, flooded and drained by tides

Continental Shelf

Submarine extension of continental landmass

Abyssal Plain

Sediment resting on oceanic crust

Soil

Loose sediment containing organic matter that accumulates in contact with the atmosphere

Topsoil

Upper zone, usually sand and clay mixed with humus

Humus

Organic matter derived from plant debris

O Horizon

Topsoil richest in organic matter

E Horizon

Zone of leaching (most extensive in humid climates)

B Horizon

Zone of accumulation (contains soluble minerals like calcite in arid climates)

C Horizon

Coarsely broken up bedrock

Caliche

CaCO3 produced by groundwater evaporation (indicative of dry and warm conditions)

Laterites

oxide rich soils produced in tropical regions

Paleosols

soils in the geologic record

Striations

scratches produced by glacial motion

Varved deposits

seasonal deposition, calm conditions

Glacial Till

unsorted, heterogenous material

Tillite

Lithified till

Dropstones

scattered coarse sediments found in finer sediments, ice rafted, can be in terrestrial or marine

Playa lake

associated with evaporites

In dunes, sand accumulates on the ___ side

leeward

Mudcracks

form through alternating wetting and drying

Alluvial fan

low, cone shaped structures that develop where the mountain slope meets the valley floor

Braided stream

more sediment available than the water can transport

Meandering River

abundant water relative to sediment

Flood Plains

Mud and fine sediment settles out where the stream overflows

Point bar

river is slowest on the inner bend, leads to accumulation of sand

Cut bank

river is the fastest, erodes the band

Natural levees

form during floods, coarsest sands deposited first, then finer sediments

Delta

depostitional body of sand, silt, and clay

Delta plain

layers of sand and silt deposited as rivers near the sea

Delta front

silt and clay deposited on slope

Prodelta

clays deposited by freshwater plume

Delta progrades into basin

sediments coarsen upward

Mississippi River Delta

Active lobe where delta is growing, has switched lobes in the pa

Abandoned lobe

Sediments undergo compaction, lobe shrinks, new lobe forms on top

Barrier Islands

Waves and currents pile up sands, longshore current

Lagoons

protected from strong waves behind barriers, mud and muddy sands

Progradation

shoreline advances seaward, requires lots of sediment

Tempesites

storm deposits on the shelf, sand beds deposited within normal muds and muddy sands

Reef front

seaward, talus slope where debris accumulates

Barrier reef

elongated reef with a lagoon behind

Fringing reefs

grow along coast, lack lagoon

Atolls

reefs on volcanic islands

Darwin

formed by sinking sand

Buried atolls

important petroleum reservoirs (ex. Texas)

Carbonate platform

broad carbonate structure above seafloor, windward side is nutrient rich with abundant reefs

Stromatolites

cyanobacteria mats that trap sediments that grow through accumulation of sediments and migration of microbes, layered with organic rich and poor muds

Living stromatolites

found in hypersaline, supratidal and intertidal settings (Sharks Bay, Australia)

Turbidity current

dense sediment laden flow driven by gravity

Turbidite

produces graded deposit, poorly sorted coarse grains at base and fine grains at top, common in canyons

Pelagic sediment

fine grained sediments accumulate by settling CaCO3, silica, and clay

Calcareous ooze

accumulations of planktonic organisms (forams, nano plankton), occurs above ~4km water depth

CCD

calcium compensation depth

Principle of Superposition

strata are layered from the oldest on the bottom to the youngest on the top

Principle of Original Horizontality

sedimentary layers are deposited as almost horizontal beds, folding and faulting deforms beds

Principle of Lateral Continuity

strata are initially deposited as continuous beds but may be subsequently eroded

Principle of Unconformities

gaps in the rock record can arise from either a hiatus in sedimentation or erosion prior to further sedimentation

Non conformity

boundary between non sedimentary rocks and overlying sedimentary strata

Angular unconformity

boundary between underlying strata that have been deformed then eroded, and overlying strata

Disconformity

boundary between sedimentary strata that has been eroded

Paraconformity

gap in the sedimentary sequence due to non deposition

Principle of Fossil Succession

sedimentary rocks may contain fossils or fossil assemblages that reflect an ordered succession

Principle of Cross Cutting Relationships

features that cross cut strata must be younger than the strata

William Smith

made the first geological map of a country in 1815

Photosynthesis equation

CO2 + H2O → CH2O + O2

Respiration equation

CH2O + O2 → CO2 + H2O

Anoxia

absence of oxygen