GEOL 107 Study Guide - Final Guide: Great Oxygenation Event, Cambrian Explosion, Marinoan Glaciation

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2: Dating the History of Life
Steno’s Three Principals: superposition, law of original horizontality, law
of original continuity
superposition: oldest rocks found at bottom (deposited first) & youngest
at top (deposited last)
Law of Original Horizontality: strata are deposited in horizontal layers
that are parallel with each other
Law of Original Continuity: strata are deposited in horizontal layers
that are continuous over lateral distance
correlation: matching of rock layers from one area to another
biostratigraphy: subdivision of geological time using divisions based on
their fossil content
Eon: Archean (4.6-2.5 Ga), Proterozoic (2.5Ga-540 Ma), Phanerozoic (540Ma-
Era: Phanerozoic (3 eras)
Paleozoic (2.5Ga-250 Ma): Age of trilobites, brachiopods & other archaic
invertebrates in the seas. First land plants, amphibians & reptiles
occur late in this era
Mesozoic (250-64 Ma): Age of dinosaurs. Ammonites, ichthyosaurs &
plesiosaurs in the seas.
Cenozoic (64Ma-present): Acme of mammals, birds & flowering plants.
Hominids appear late in this era.
Late Proterozoic: Ediacaran
Paleozoic: Cambrian, Ordovician, Silurian, Devonian, Carboniferous,
Mesozoic: Triassic, Jurassic, Cretaceous
Cenozoic: Paleogene, Neogene
Paleogene: Paleocene, Eocene, Oligocene
Neogene: Miocene, Pliocene, Pleistocene
radioisotopes: radioactive atoms that contain an unstable combination of
neutrons and protons
half-life: amount of time required for the amount of something to fall to
half its initial value
14C dating: dating using 14C—>14N to date organic fossils <60 000 yo — useful
for archeologists
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U/Pb dating: uranium to lead — found in zircons from volcanic ash — highly
precise for >60 000 yo
3: Plate Tectonics — How the Earth Works
plate tectonics: continents are moving at measurable speeds — major
unifying theme in earth science
Alfred Wegener: meteorologist who first preposed continental drift (early
plate tectonics)
continental drift: theory proposed by Alfred Wegener that continents
shifted position on Earth’s surface
Gondwana: megacontinent of South America, Africa, India, Antarctica &
Australia (Cambrian - Cretaceous 542-100 Ma)
Mesosaurus: freshwater reptile from Gondwana (critical evidence for
Gondwana) — Permian radiation
Glossopteris: gymnosperm (seed-fern) from Gondwana (critical evidence for
mid-ocean ridge: underground mountain range down centre of the Atlantic
that perfectly matches ‘fit’ of the continents
paleomagnetics: field that uses magnetic directions recorded in rocks to
determine latitude at which rocks were formed
subduction zones: ocean crust consumed under another plate — mountain belts
form (eg Pacific Plate & western S.America = Andes)
continent-continent collision: one continent plate is destroyed under
another — mountain belts form (eg India & S.Asia = Himalayas)
supercontinent: assembly of most or all Earth’s continents — at least 3
times in Earth history
Pangea: 300-200 Ma Carboniferous - Triassic
Rodinia: 1200-800 Ma (-end Proterozoic)
Nuna: ca. 2000 Ma first supercontinent — corresponds with Great
Oxidation Event
rift valley: beginning of continental breakup (eg East Africa rift)
linear sea: spreading of rift valleys (eg Red Sea - Gulf of Aden = Arabia &
ocean: continued spreading of rift valleys & linear seas (eg Atlantic) —
transitory features
Wilson Cycle: (Supercontinent Cycle) mega/super continents breakup &
disperse, then are destroyed when continents later collide
4: Evolution — How Life Works
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evolution: process of changes/developments in creatures over time — major
unifying theme in biology
DNA: stable material used in transmitting & holding coded genetic
gene pool: total amount of genetic information coded on all individuals in
population — raw material for specialisation
mutation: random changes in one or more nucleotides on the DNA
natural selection: process of beneficial mutation being favoured and
enhanced in a population — enhances ‘beneficial’ genes & reduces/eliminates
‘harmful’ ones
Pepper Moth: classic example of natural selection — speckled vs black
pre 1880: 99% speckled (camouflaged on lichen-covered trees)
1880-1960 industrial revolution: 99% black (soot-blackened trees)
post 1960 Clear Air Act: restore balance
Darwin’s finches: classic example of natural selection
single generalised species of finch reached Galapagos Islands
diversified into 14 species — major habitats & feeding strategies
anagenesis: continual evolution of a species until it imperceptibly becomes
a new species
cladogenesis / divergence: splitting of one species into two as different
populations of the species respond to changing circumstances in different
convergence: similar life habit in a similar environment leads to evolution
of similar morphology among organisms completely unrelated (no common
analogy: evolution leads to common function from different origins
homology: same trait present in multiple species with a shared ancestor
sabre-tooth: evolved independently at least 5 times
coevolution: organisms evolve in response to evolutionary changes in other
organisms — e.g. angiosperms & animal vectors due to seed distribution by
large animals
“Arms’s Race”: coevolution between predator and prey — hunt/avoid better
Mutualism: relationship between two species that is beneficial to both
Red Queen Effect: Van Valen — any evolutionary advance by one species
forces the rapid evolution of all species that are dependent on it — must
constantly evolve
Court Jester Effect: abiotic factors, not under the organisms control, also
shape their evolution
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