Term
| What is the nutshell version of the Solar Nebula Theory? |
|
Definition
| Gas and dust in nebulae aggregate into rotating disks that produce a star, with a disk of particles around it that condense and aggregate into zones that generate planets |
|
|
Term
| What is the accretionary origin of the Solar System? |
|
Definition
| Gas and dust in nebulae aggregate into rotating disks that produce a star, with a disk of particles around it that condense and aggregate into zones that generate planets |
|
|
Term
| How long ago were the sun and planets formed? |
|
Definition
|
|
Term
| What kind of star is the sun considered? |
|
Definition
|
|
Term
| Did the sun and planets all form around the same time? How do you know? |
|
Definition
| Yes. They all have similar rotation & orbit in the same place. |
|
|
Term
| Name and describe the three steps of the Solar Nebula Theory. |
|
Definition
1) Nebular cloud contract to central ball with 90% mass & turbulent, rotating outer disk
2) Solids condense in nebula
- heavy elements condense to refractory
rocks in inner area (high temps)
- lighter elements condense to ices in outer areas (low temp)
- ‘snow line’ at 2.7 astronomical units (AU)
3) Sun forms: gravitational contraction heats and starts thermonuclear fusion reactions, igniting in an explosive blast drives light materials out of inner areas of solar nebula |
|
|
Term
| What type of planets accrete from solids? |
|
Definition
|
|
Term
| What slows the sun's rotation? |
|
Definition
| Magnetic fields of Sun & nebula interaction |
|
|
Term
| What is the residual material on the edge of the solar system? |
|
Definition
The Kuiper Belt that contains small icy planetoids like Pluto.
The Oort cloud in the outer zone with comets. |
|
|
Term
| How and where did the earth form? |
|
Definition
1. accretion of rocky materials (chondrules)
2. condensed in inner parts of solar nebula |
|
|
Term
| What metals are abundant on Earth? What is important about these minerals? |
|
Definition
| Fe, Mg, Al, Ni, Ca, Na, K. They are more abundant than elsewhere in the galaxy. |
|
|
Term
| What gasses are rare on Earth? Why? |
|
Definition
H2 & He gases nearly lacking.
Earth cannot retain them. |
|
|
Term
| What gasses are rare on earth that are abundant elsewhere in the cosmos? |
|
Definition
| Neon, argon, krypton & xenon |
|
|
Term
| Why is solar system enriched in heavy elements? |
|
Definition
Heavy elements are formed by the thermonuclear fusion reactions in interior of stars. Heavier elements are formed by neutron capture; they are
the “waste products” of fusion reaction. |
|
|
Term
| Name the fusion reaction series. |
|
Definition
H - He (main energy source)
He - C at higher temps
C cycle produces N & O, F, Ne, Na, Mg, P, S, and Fe |
|
|
Term
| What are the mechanisms for distributing heavy elements to the nebula? |
|
Definition
| Nova & supernova explosions of stars blast gas into space, spreading nuclear waste through galaxy, which enriches the nebular cloud with heavy elements. |
|
|
Term
| What happened to Earth's early atmosphere? |
|
Definition
| Original atmosphere of Earth lost by solar blasting, Resulting in loss of neon, argon, krypton & xenon. |
|
|
Term
| What was earth's replacement atmosphere composed of, and what created it? |
|
Definition
| N2, CO2, H2O, HCl, Volcanic emissions. |
|
|
Term
| What is a unique feature of earth? Why is it unique? |
|
Definition
Liquid water. Earth was cool enough for water vapor to condense
and form oceans. |
|
|
Term
| What produced ocean chemistry in the past similar to today's oceans? |
|
Definition
| HCl (acid) would dissolve in water to form acidic oceans and rain, that in turn would rapidly react with exposed rocks (weathering). Resulting chemistry produce ocean water similar to modern oceans. |
|
|
Term
| What temperature did Earth initially heat to? What happened at this temperature? |
|
Definition
| 2000C. Earth melted and volatile gasses were lost. Melting caused separation of immiscible materials. |
|
|
Term
| What two elements compose the core of the Earth? |
|
Definition
|
|
Term
| What elements compose the crust of the Earth? |
|
Definition
| Ca, K, and Na, and some O, Si, Al, & U |
|
|
Term
| What elements compose the mantle? |
|
Definition
| Residual Fe & Mg silicates and metal oxides |
|
|
Term
| What was the dominant event of early Earth? How early did it happen? |
|
Definition
| Core formation. Core of Earth formed within 30 million years of Earth origin. |
|
|
Term
| Why did early earth heat? |
|
Definition
| Early Earth heated because of gravitational contraction, meteoroid bombardment, and radioactive decay |
|
|
Term
| What is the driving force for Earth interior processes? What is this the concept of? |
|
Definition
| Internal heat. Solid earth. |
|
|
Term
| What is the cause of the surface heat budget? What is this the concept of? |
|
Definition
Solar heat: drives flow of air and water
Surface heat budget is mostly from solar radiation. Fluid Earth. |
|
|
Term
| When did the melting of planets occur? |
|
Definition
|
|
Term
| When was the lithosphere formed? |
|
Definition
| 4.4 b.y., with water-laden surface. |
|
|
Term
| During the crust segregation, what was the continental crust composed of? |
|
Definition
|
|
Term
| Was earth's surface ever composed of magma oceans? |
|
Definition
|
|
Term
| What is a Craton? When did they form? |
|
Definition
| Cratons are areas of stabilized continental crust which are less effected by tectonic movements, underlain by a 'root' of upper mantle. The stable zone extends 200km deep. They are mostly metamorphic & igneous rock units. They formed 3.0 b.y. ago. |
|
|
Term
| What removed Earth's inherited atmosphere, and what replaced it? |
|
Definition
Solar blasting removed inherited atmosphere;
Replacement atmosphere produced by volcanism |
|
|
Term
| What did smelting do in earth's early history? |
|
Definition
| Smelting of accreted solids produce liquid iron that settled to form core and light liquids that rose to form continental crust; Results in forming zonal structure of Earth |
|
|
Term
| What is the composition and characteristic of the upper mantle? |
|
Definition
| Upper mantle is composed of melt-depleted peridotite (depleted in Ca, Al, Fe, which go readily into melt); makes it more bouyant and rigid than surrounding mantle. |
|
|
Term
|
Definition
| exposed area of cratons have plain, flat surfaces (from long erosion) |
|
|
Term
| What countries contain the oldest rocks? |
|
Definition
|
|
Term
| What is the age of the oldest rocks on earth? |
|
Definition
| Oldest rocks on Earth are 4.28 b.y |
|
|
Term
| What is the oldest kind of crystal? |
|
Definition
| Zircon which has dated to 4.4 b.y. old. |
|
|
Term
| What is Numerical Dating? |
|
Definition
| quantitative measurements of time (e.g., radioactive decay) that involve time-dependent processes; no addition or loss of parent or decay material in system |
|
|
Term
|
Definition
identifying unique intervals of
geologic time (e.g., dating with fossils) |
|
|
Term
| what is inferential dating? |
|
Definition
| determines age by comparison to known sequence of events (e.g., magnetostratigraphy) |
|
|
Term
| What is Radiometric dating? What is the concept of it? |
|
Definition
| Numerical age determination of materials containing radioactive isotopes. Naturally occurring radioactive atoms change to other atoms by spontaneous decay. |
|
|
Term
|
Definition
The release of alpha particles. atomic number decreases by 2, atomic weight decreases by 4
Ex. U_92 -> Th_90 |
|
|
Term
|
Definition
release of an electron from the nucleus.
atomic number goes up by 1, atomic weight unchanged (0).
Ex. C_6 -> N_7 |
|
|
Term
| What is Electron capture? |
|
Definition
electron is captured by a proton, turning it into a neutron.
Atomic number goes down one.
Ex. K_19 -> Ar_18 |
|
|
Term
| What is Spontaneous fission? |
|
Definition
disintegration of
a heavy nucleus into large fragments;
usually two fragments with masses near
95 and 137
example: 238^U_92 → Ba_56 + Kr_36 + 3 n |
|
|
Term
|
Definition
| (atomic disintegration)/(unit time) = (decay constant)*(atoms present) |
|
|
Term
|
Definition
time needed for 1/2 of parent to decay to
daughter product |
|
|
Term
| Describe the U/Pb dating method. |
|
Definition
Decay of U-235 & U-238 to isotopes of lead
Measure amounts of uranium and lead isotopes
and compare ages calculated from co-occurring
U-235→Pb-207 and U-238→Pb-206 decay;
both ages should be the same (be concordant).
Accurate dating depends on maintaining a
closed system for parent and decay product |
|
|
Term
|
Definition
| A material (mineral, rock, etc.) that has not lost or added parent or decay components (radioisotopes, etc.) after formation. |
|
|
Term
| What does a valid age date depend on? |
|
Definition
| depends on meeting the condition that there was no addition or loss of parent or decay product in the system |
|
|
Term
| What happens if loss of decay isotopes has occurred in a rock and you try to radio-metrically date it? |
|
Definition
Loss of decay isotope leads to calculating a
younger age than the time of rock formation. |
|
|
Term
| What are the major numerical dating methods? |
|
Definition
| Major numerical dating methods are U-Pb, Rb-Sr, K-Ar, and C14 |
|
|
Term
| What is the K-40->Ar-40 Dating method best for? |
|
Definition
| Method best for dating volcanic rock and minerals. |
|
|
Term
| Describe the K-40→Ar-40 dating method and why it is used. |
|
Definition
1) Pre-existing argon lost from magma.
2) At cooling, new (radiogenic) argon is retained in mineral or rock
3) As rock cools below closure temperature it forms a closed system.
Age is determined by the time since the material began to retain argon. |
|
|
Term
| What allows the dating of metamorphism of heated rock? |
|
Definition
| Subsequent heating allows argon gas to escape - so, can date time of metamorphism using K-Ar method. |
|
|
Term
| What dating method is used in conjunction with the K-Ar method? |
|
Definition
40Ar/39Ar DATING METHOD.
In addition to natural decay of K-40 to Ar-40, a sample is irradiated to convert K-39 to Ar-39 and both Ar decay isotopes are measured. The increased accuracy of measuring Ar isotopes in the same step is more accurate than measuring K and Ar separately. Useful limit for C-14 dating 60,000 years. [Useful range for age dating is about 10 half-lives of the isotope used.] |
|
|
Term
| Explain the C14 Dating method |
|
Definition
| When organism alive, C-14 level nearly constant (continual intake of C-14). At death, C-14 level begins to decrease. Measure C-14 remaining in sample to determine age. |
|
|
Term
| What is the half life of C14? |
|
Definition
| Half-life for C-14 is 5730 years |
|
|
Term
| What is C14 dating used for? |
|
Definition
| Dating once-living material. |
|
|
Term
|
Definition
| C-14 formed from N-14 in atmosphere, by cosmic ray bombardment, via electron capture. |
|
|
Term
| When is C14 dating inaccurate? |
|
Definition
|
|
Term
| What is Cosmogenic Nuclide dating? What does it do? |
|
Definition
| Measures accumulation of new radioactive isotopes, produced by exposure to cosmic radiation. Cosmic rays affects materials within a few meters of ground surface. |
|
|
Term
| What is Cosmogenic Nuclide used to date? |
|
Definition
| Dates ice, lake sediments, and exposure surfaces on rock. |
|
|
Term
| What is the best ratio of elements for Cosmogenic Nuclide dating? |
|
Definition
|
|
Term
| What are the limits of Cosmogenic Nuclide dating? |
|
Definition
Dating limit for exposure surfaces is the saturation level,
when new nuclei balanced by loss.
Saturation level occurs after a few half-lives
At saturation level, decay rate equals accumulation rate
Each radionuclide will have separate saturation level
The ratio of 26Al/10Be will continually change until both reach saturation, making calculation of age possible. |
|
|
Term
| What is Fission Track dating? What minerals does it work best with? What is the name for the temperature that material must remain under? |
|
Definition
Heavy radioactive decay particles (fission fragments) produce tunnel of damage in mineral or glass.
These fission tracks are up to 15 microns long
Method works well with zircon and glass.
Material must remain below annealing temperature. |
|
|
Term
| How is age determined by Fission Track dating? |
|
Definition
1) counting number of fission tracks per unit area
(= daughter product)
2) annealing surface to remove tracks
3) irradiate to induce fission of remaining radioactives
4) count number of new fission tracks (= parent material) |
|
|
Term
| What is Dendrochronology? |
|
Definition
Age dating using annual tree growth bands
Growth bands record environmental variation in addition to age. A specimen is matched to a dated standard. |
|
|
Term
| What is Sclerochronology? |
|
Definition
Determining age, growth rate and environmental variation using periodic (annual, monthly, daily) growth
increments in skeletons.
(Corals, molluscs, brachiopods) |
|
|
Term
| What is Magnetostratigraphy? |
|
Definition
Layered rocks contain history of Earth's magnetic field through time.
Earth's magnetic field is global in extent.
- changes polarity
- reversal occurs quickly - a global time horizon
- intervals between reversals have different duration. |
|
|
Term
| Name the inferential dating methods. |
|
Definition
DENDROCHRONOLOGY
SCLEROCHRONOLOGY
MAGNETOSTRATIGRAPHY
ASTROCHRONOLOGY
STABLE ISOTOPE STRATIGRAPHY
EUSTATIC SEALEVEL CURVES |
|
|
Term
| Name the numerical dating methods. |
|
Definition
RADIOMETRIC DATING
COSMOGENIC NUCLIDE DATING
FISSION TRACK DATING |
|
|
Term
| What is the neogene record? |
|
Definition
Record of reversals in direction of
Earth’s magnetic field during last 5 million years. Used with Magnetistratigraphy. |
|
|
Term
|
Definition
| An inferential dating method that uses Milankovich orbital variations of the Earth to subdivide time. |
|
|
Term
| What are Milankovich orbital variations? |
|
Definition
Produce variations
in insolation of solar
radiation. This type
of variation has
been determined for
the past 40 million
years. |
|
|
Term
|
Definition
| Amount of solar radiation received on a surface. |
|
|
Term
| What is stable isotope stratigraphy? |
|
Definition
Measures concentrations of stable isotopes.
- increase of radiogenic daughter products
- variation in amounts stored oceans, mantle, etc. |
|
|
Term
| When was the Earth formed? |
|
Definition
|
|
Term
| What is O18/O16 stratigraphy? |
|
Definition
measurements of Isotope ratios controlled by temperature, & ice volume;
can determine paleotemperatures |
|
|
Term
| What is C13/C12 stratigraphy? |
|
Definition
| Storage of organic carbon (photosynthesis uses one isotope) in sediments changes isotope ratios of water,etc. |
|
|
Term
|
Definition
| measurements of Increasing amounts of Sr87 added by radioactive decay |
|
|
Term
| Name the Relative dating methods. |
|
Definition
PRINCIPLE OF BIOTIC SUCCESSION
PRINCIPLE OF SUPERPOSITION
CROSS-CUTTING RELATIONS |
|
|
Term
| What is the principle of biotic succession? |
|
Definition
Fossils and fossil assemblages change through a stratigraphic section and do not repeat. Each stratigraphic section is unique.
Based on the Principle of Organic Evolution |
|
|
Term
| What is the principle of superposition? |
|
Definition
| In an undisturbed sequence of sediments, younger deposits occur at at the top and older at the bottom |
|
|
Term
| What is the principle of cross-cutting relations? |
|
Definition
| A rock unit which intrudes another is younger than the surrounding rock unit |
|
|
Term
| What is the principle used to define units of the geologic time scale? |
|
Definition
| PRINCIPLE OF BIOTIC SUCCESSION |
|
|
Term
| Define the two correlaries of the principle of superposition. |
|
Definition
Correlary 1 -- Principle of original horizontality
Sediment strata are deposited as horizontal layers.
Correlary 2 -- Principle of original lateral continuity
Strata originally extended in all directions until they thinned to zero |
|
|
Term
| Define the Eustatic Sealevel curves |
|
Definition
Changes in sealevel are global:
they provide another method for inferential dating of strata.
Transgressions and regressions of
sedimentary cycles (T-R cycles) are used to correlate stratigraphic sections |
|
|
Term
| Name and define the causal mechanisms of Eustatic Sealevel Change. |
|
Definition
Short term control (100,000 years or less): Storage of water on land in continental glaciers
Long term control (10s-100s millions of years): Change in volume of mid-ocean ridges by changing rate of mantle upwelling (as shown by rate of seafloor spreading) |
|
|
Term
|
Definition
a break in deposition for a long time interval; shows relation between tectonism, erosion, and sedimentation
the result of deposition during sealevel or baselevel change in a basin. Most are global; produced from eustatic changes. |
|
|
Term
|
Definition
migration of a shoreline away from center of an ocean basin, covering land with water.
Sedimentary environments (facies) shift landward; seaward facies overlie more landward facies |
|
|
Term
|
Definition
migration of shoreline towards center of ocean basin, exposing more land.
Sedimentary environments (facies) shift seaward; landward facies overlie more seaward facies. |
|
|
Term
| Why do Transgression/Regression cycles occur? |
|
Definition
1) sealevel rises or falls
2) land sinks or rises
3) shorelines are filled in with sediment deposit |
|
|
Term
|
Definition
| Surface created by erosion or non-deposition. |
|
|
Term
|
Definition
| Sediments overlie igneous/metamorphic rocks. |
|
|
Term
| What is an Angular Unconformity? |
|
Definition
| Sediments overlie tilted strata. |
|
|
Term
|
Definition
Lateral changes in sediments of age-equivalent deposits that result from deposition in different depositional environments.
Different types of sediments are deposited in different depositional environments. |
|
|
Term
| What are the two predictable patterns that Facies occur in gradients of? |
|
Definition
1) elevation - depth
2) climate gradient |
|
|
Term
| What is the reason for defining facies? |
|
Definition
Because we want to know the age of
the deposits and the environment in which they accumulated. Sediments contain indicators of those environments in the form of contrasting lithology, sedimentary structures, fossils and chemistry |
|
|
Term
|
Definition
| For sediments deposited during a transgression or regression, laterally adjacent facies will occur above or below the other in a conformable vertical sequence of deposits. |
|
|
Term
| What is the make-up and age of the oldest fossils? |
|
Definition
| 3.5 b.y. old prokaryote filaments on pillow basalts, round spheroids (single cells),filamentous strands, stromatolite layers in rock. |
|
|
Term
| What element indicates oxygenic photosynthesis? |
|
Definition
|
|
Term
|
Definition
| Layers of sediment formed by mats of microbes(mostly cyanobacteria - bluegreen algae), in laminated deposits, shaped into planar and domal shapes due to mucilage secretions that trap sediment particles and cause them to try to grow past the sediment layer. Sediment is then quickly cemented into place. |
|
|
Term
| What is the first described Precambrian microbiota? |
|
Definition
| Gunflint Chert Microbiota. |
|
|
Term
| How old is Gunflint Chert Microbiota? |
|
Definition
|
|
Term
| What is Gunflint Chert Microbiota compsed of? |
|
Definition
Filamentous cyanobacteria, single cell (coccoid) cyanobacteria.
They are considered microbes with unusual morphology, and are preserced in microcrystalline chert (quartz). Very typical of precambrian microfossilization preservation. |
|
|
Term
| What is special about Gunflint Chert Microbiota? |
|
Definition
| Contains prokaryotes and probable eukaryote cells. |
|
|
Term
|
Definition
-Lack nucleus with concentration of
genetic material
-lack organelles in cell
-reproduce by binary fission at most times |
|
|
Term
|
Definition
-has membrane-bound nucleus (genetic
material), mitochondria, plastids,
endoplasmic reticulum, & organelles
-meiosis and mitosis in cell division |
|
|
Term
| What is the Endosymbiont theory of eukaryote origin? |
|
Definition
The theory that Common eukaryotes arose from symbiosis of host cell
and specialized prokaryote bacteria
1. Primitive eukaryotes (e.g. Giardia) appear with membrane-bound nucleus and distinctive rRNA but lack
organelles
2. Host cell acquires bacteria symbionts, which become organelles (mitochondria, chloroplasts, flagellae, etc)
3. Multiple origins
-Host with mitochondria and flagellae are animal type and form the base of metazoan diversification
-Host with mitochondria and chloroplasts are plant type and form the base of algal-plant diversification |
|
|
Term
|
Definition
Microbes that oxidize inorganic ions to get energy (H2S, NH3, Fe++). Fe-reducing bacteria Fe & Mn-oxidizing bacteria
methanogens - use H2 to reduce CO2 to CH4 |
|
|
Term
|
Definition
| Microbes that are chlorophyll-bearing and use light energy to make food from CO2 |
|
|
Term
|
Definition
| Microbes that consume organic molecules for food; require O2 the process of respiration uses O2 , and produces more energy than anaerobic processes (fermentation) |
|
|
Term
| What is the relationship between CO2 and O2 in the atmosphere? |
|
Definition
| CO2 content of atmosphere drops as O2 content increases. |
|
|
Term
| What are the indications of the early anoxic atmosphere? |
|
Definition
Early Precambrian sediments indicate non-oxidizing surface conditions
- sediments dark colored
- pebbles lags of pyrite (FeS2), siderite (FeCO3), & uraninite
- sediment sulfur isotope ratios require anoxic conditions
- redbeds |
|
|
Term
| When did the indicators of the anoxic atmosphere disappear? |
|
Definition
| Indicators of anoxia disappear about 2.4 b.y. ago, indicating rapid rise of O2 between 2.3-2.0 b.y. ago |
|
|
Term
| Define the Great Oxygenation Event |
|
Definition
Rapid rise in O2 levels between 2.3-2.0 b.y
Oxygen (O2) increases and CO2 begins great decline in atmosphere. A vast example of climate change as an unavoidable consequence of life releasing waste products.
This is a terraforming event, comparable to Mars loss of atmosphere and to Venus falling into a greenhouse furnace condition |
|
|
Term
|
Definition
Banded Iron Formation sediments.
-Common before the great oxygenation event, 2.5-1.8 b.y. ago during middle of Precambrian period.
Extensive, thin layers of Fe oxides & SiO2 deposited on continental shelves |
|
|
Term
|
Definition
Source of dissolved Fe and silica:
Rain water contains carbonic acid (H2CO3) from water vapor and CO2
in atmosphere. Carbonic acid destroys silicate minerals on land, releasing ions
Fe and Si ions carried to sea by runoff
Ferrous Fe and Si ions accumulate in alkaline ocean water
Process of formation:
Photosynthesis by algal microbes releases waste oxygen. Oxygen combines with dissolved ferrous Fe ions and dissolved Si
Precipitates form of iron oxide and silica
Precipitates settle to seafloor to form thin layers of BIFs during blooms of phytoplankton, creating banded deposits |
|
|
Term
|
Definition
| Records episodic growth of microbes |
|
|
Term
| What is the Pasteur Point? |
|
Definition
| When the O2 levels in the atmosphere reached an oxygen concentration at 1% of present levels, between 1.8-1.5 b.y. ago |
|
|
Term
| What did the Pasteur Point allow and correspond to? |
|
Definition
This condition allows eukaryotic organisms to flourish
Corresponds to time of change in deposition from BIFs to carbonates (limestone) and sulphate-rich (gypsum,
anhydrite) sediments
- marked by appearance of redbeds (Fe oxide stained seds) |
|
|
Term
| Define the Formation of the Ozone Layer and what it does. |
|
Definition
When the O2 in the upper atmosphere became O3, ozone.
Ozone layer forms barrier to ultraviolet radiation
Develop from water vapor and O2 in atmosphere
- low levels in early Precambrian
-increase in late Precambrian with buildup of O2 |
|
|
Term
| What is the Neoproterozoic Oxidation Event? |
|
Definition
Second rapid increase in O2, to 10% of present levels, occurred between 0.7
and 0.6 b.y. (700-500 m.y.), with oxygenation of deep ocean bottom
waters. It is when multicellular fossils began appearing. Time of great tectonic/climatic/chemical changes. |
|
|
Term
| Is there a relationship between tectonism and global climate change? |
|
Definition
| Yes, and it is shown by CO2 and life (O2). |
|
|
Term
| What happens to increase CO2? |
|
Definition
Increasing CO2:
gases emitted by volcanoes; amount controlled by rate of volcanic activity, related to plate movements |
|
|
Term
| What happens to decrease CO2? |
|
Definition
CO2 consumed by weathering of silicate rocks on continents; CO2 and H2O combine to form carbonic acid (in rainwater), that destroys minerals and consumes CO2 (converts to CaCO3 =limestone)
[- from Devonian and younger, coal deposition also stores CO2 as carbon rock (=coal)] |
|
|
Term
| Describe the snowball earth theory. |
|
Definition
Hypothesis: Widespread continental glaciers and global sea ice cover!
Evidence: unsorted sediment (tillite?) on most continents, at low latitudes; capped with carbonates
Effects: increase in ice cover increases Earth albedo, decreasing radiant energy retained by Earth, further cooling Earth
-lowers weathering rates
Consequence: CO2 not consumed or buried, resulting in increased CO2 in atmosphere and rapid global warming that ends Icehouse |
|
|
Term
| What happens when sealevel covers land? |
|
Definition
lowers albedo; increased retention of
solar heat. high pCO2 in atmosphere. |
|
|
Term
| What happens when the formation of glaciers lowers sealevel? |
|
Definition
| increased albedo from ice lowers mean global temperatures. continental glaciations occur. |
|
|
Term
| What are the icehouse-hothouse climate cycles? |
|
Definition
Cyclic variations in glaciation intervals (icehouse) and high global
temperature intervals (hothouse)
Last 1 billion years have 3 icehouse events and 2 hothouse events
Climate heat is result of solar radiation (insolation), Earth reflection (albedo) and atmosphere content of greenhouse gas |
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Term
| Date the two late Proterozoic glaciations. |
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Definition
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