GEOL 106 FINAL EXAM KRISTIE

What is the Big Bang Theory?

The theory that the universe began as a singularity and expanded 13.8 billion years ago

What evidence supports the Big Bang Theory?

Cosmic microwave background radiation, galaxy redshift, and abundance of light elements.

What is the Solar Nebula Theory?

Explains solar system formation: a rotating cloud of gas and dust collapsed, forming the sun and planets

What is differntiation of Earth?

Separation of materials by density during Earth's molten stage, forming core, mantle, and crust.

What do meteorites tell us about Earth's age?

radioactive dating of meteorites gives ~ 4.6 billion years

How old is Earth?

about 4.6 billion years

What is relative dating?

determining the sequence of events without exact dates

What is absolute dating?

Determing numerical ages using radioactive decay

Principle of Superposition?

In undisturbed strata, oldest layers are at the bottom

Principle of Original Horizontality?

Sedimentary layers are deopisted horizontally.

Princple of Cross-cutting Relationships?

a feature that cuts through rocks is younger than the rocks

Principle of of inclusions?

INCLUSIONS, or fragments of one rock contained in another, are OLDER than the rock they are found in

What is an unconformity?

a gap in the geologic record due to erosion or non-deposition

Principle of lateral continuity?

sediment extends laterally in all directions unit it thins and pinches out or terminates against the edge of the deopositional basin

Types of unconformities?

disconformity, angular unconformity, nonconformity

What is a Hiatus?

any interval of geologic time not represented by strata in a particular area

What is disconformity?

a surface of erosion or nondeposition between younger and older beds that are parallel beds

What is angular unconformity?

an erosional surface on tilted or folded strata over which younger strata have been deposited

What is a nonconformity?

erosion surface cut into metamorphic or igneous rocks is covered by sedimentary rocks

What is stratigraphic correlation?

matching rock layers across regions using fossils and lithology

What is radiocarbon dating used for?

dating organic material up to ~ 50,000 years old

What is radioactive decay?

the process whereby an unstable atomic nucleus is spontaneously trasnformed into atomic nucleus of a different element

What is dendrochronology?

another useful method for dating geologically recent events. Age of the tree can be determined by counting the tree rings

Who proposed natural selection?

Charles Darwin

What is Lamarck's theory?

Traits acquired during life are inherited (disproved)

What did Mendel contribute?

Principles of inheritance through pea plant experiments

Define mutation.

a change in DNA sequence that can lead to variation

What is speciation?

Formation of new species through evolutionary processes.

Homologous vs. Analogous structures?

homologous: same orgin, different function

Analogous: different origin, same function

What are vestigial structures?

reduced structures with no current function (e.g., human appendix)

What is fossilization potential?

Likelihood of an organism becoming a fossil; higher for hard parts

Types of fossil preservation?

Unaltered remains, permineralization, recrystallization, replacement, carbonization

Large Ice Age mammals in frozen ground (rare).

Freezing

Air drying and shriveling of soft tissues (rare).

Mummification

Insects in hardened tree resin.

Preservation in amber

Bones in asphalt-like substance at oil seeps (rare).

Preservation in tar

Original composition and structure retained

Unaltered Remains

Change in composition and/or strucure of original.

Altered Remains

Addition of minerals to pores and cavities

Permineralization

Change in crystal structure, e.g., aragonite recrystallized as calcite

Recrystalization

One chemical compound replaces another, e.g., pyrite replaces calcium carbonate; silicon dioxide replaces wood

Carbonization

Burrows, tracks, trails, nests, droppings (coprolites), or any other indication of organic activity

Trace fossils

A cavity having the shape of a bone or shell

mold

A mold filled by minerals or sediment

cast

Difference between molds and casts?

mold: impression of organism

cast: filled mold

What eon is in the Precambrian?

Hadean, Archean, Proterozoic

What is the Hadean Eon?

earliest eon, no rocks preserved, Earth was molten

no ozone/high UV radiation

earliest crust likely formed

no oxygen

Oldest known mineral?

Zircon crystals (~4.4 Ga)

Oldest rocks?

Acasta Gneiss (~4.03 Ga)

What are greenstone belts?

Archean rock assemblages with volcanic and sedimentary units

What is a craton?

Stable interior of a contient

What are Banded Iron Formations (BIFs)?

Alternating iron-rich and chert layers, formed 2.5-1.5 Ga

does not form today

What is Snowball Earth?

Hypothesis that Earth was globally glaciated during Proterozoic

What are stromalites?

Layered structures formed by cynobacteria, earliest evidence of life (~3.5 Ga)

Oxygen accumulates through?

photosynthesis (cyanobacteria)

How did the magnetic core established?

inner/outer core differentiated

What lived in the Archean time?

only bacteria

What is the origin of life in the precambrian?

elements combine to for amino acids, linked to form proteinoids

needed energy source

Who recreated energy source lab experiments?

Stanley Miller

able to synthesize amino acids in reducing environment

What are hydrothermal vents?

possible location of origin of life

hot water expelled from deep ocean floor

many unusual species live in extreme conditions

What are stromolites?

"fossils" of cyanobacterial mats/mounds

sediment trapped by sticky coating

oldest true record of life

What was life before cyanobacteria?

simple, single celled, prokaryotic, anaerobic bacteria.

no definitive evidence yet found

What are eukaryotic cells?

more complex than prokaryotes

possible chemical evidence in rocks at 2.7 GA

oldest true fossil example 1.2 Ga

Originate through symbiotic relationship between prokaryotes

When was the Paleozoic Era?

542-245 Ma

What periods are in the Paleozoic?

Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian

What happened at the end of Proterozoic?

Rodinia breaking up

six major continents, smaller microcontinents

Earth in the Cambrian?

6 continents, near equator

ice free poles

continents drowned

Earth in the Ordovician?

Gondwana moves towards south pole

Earth in Silurian?

Baltica & Laurentia collide

Earth in Devonian?

Laurasia & Gondwana converge

Laurasia & Baltica- orogeny

Earth in Carboniferous?

Glaciation at south pole (Gondwana)

Gondwana moves north, collides with Laurasia

Earth in Permian?

Pangaea forms

What was Pangaea?

Supercontinent formed during Permian

Climate changes, arid conditions and rain shadow

What is cyclothem?

Alternating marine and nonmarine sediments due to sea-level changes.

What are the 4 squence stratigraphy are in the Paleozoic?

Sauk, Tippecanoe, Kaskaskia, Absaroka

What is the Sauk Sequence?

Transgressive sequence from Late Proterozoic to Early Ordovician

carbonates, stromatolites, reefs

What is the Tippecanoe Sequence?

A sequence of Ordovician to Lower Devonian sediments bounded above and below by regional unconformities and recording an episode of marine transgression, followed by full flooding of a large region of the craton and subsequent regression.

What is the Kaskaskia Sequence?

Devonian reef complex in Canada, then widespread black shales in North America

What is the Absaroka Sequence?

Rocks deposited during the Pennsylvanian through Early Jurassic

What was the Cambrian Explosion?

Rapid diversification of life ~535-520 Ma

What is Small Shelly Fauna?

Early organisms with hard parts

What are the advantages for the small shelly fauna?

UV protection

prevents desiccation

allows for increase in size

protection against predators

What caused the Permian mass extinction?

greatest recorded mass extinction ever

Likely volcanism, global cooling, or other factors

What are mass extinctions?

when many types of organisms become extinct at the same time

What are background extinctions?

extinctions that occur continuously but at a very low rate

What are the "Big Five"?

End of Ordovician

End of Devonian

End of Permian

End of Triassic

End of Cretaceous

What is an amniotic egg?

Egg with protective covering allowing reproduction away from water

What are tetrapods?

Four-limbed vertebrates (amphibians, reptiles, mammals, birds).

Fish in Paleozoic?

jawless fish, placoderms

lobe finned fish

ray finned fish

Lobe finned fish?

developed abilitiy to use muscular fins to maneuver in shallow water

led to amphibians/tetrapods

Amphibians in Paleozoic era?

evolved from lobe finned fish

joined plants, insects on land

need water to lay eggs

Reptiles in the Paleozoic era?

amniotic egg

Late Mississippian, 325 Ma

Pelycosaurs

Therapsids

Thecodonts

Pelycosaurs in the Paleozoic era?

fin-backed reptiles

extinct in Permian

Therapsids in the paleozoic era?

mammal-like reptiles

Thecodonts in the Paleozoic era?

ancestors of crocodiles, pterosaurs, dinosaurs

What are trilobites?

Extinct marine arthropods common in Paleozoic

When/What was the Mesozoic Era?

245-66 Ma

"Age of Dinosaurs"

Evolution of Reptiles, Mammals, Birds, Flowering Plants

What event marks the end of the Cretaceous?

K-Pg boundary mass extinction, likely due to meteorite impact

What is the Chicxulub crater?

Impact site in Yucatan linked to dinosaur extinction

Name two major dinosaur groups.

Saurischia (lizard-hipped) and Ornithischia (bird-hipped)