Exam 2 study

What is sea-floor spreading

process by which new oceanic crust is created at MOR, creating and widening ocean basins

At which tectonic boundary does sea-floor spreading occur?

Divergent

Explain the principle of Superposition

In an undeformed sequence of rock, the oldest rock can be found at the bottom of the sequence, the youngest layers at the top.

Explain lateral continuity

Sediments are deposited in continuous sheets/layers until they grade into a different sediment type or thin out

Explain original horizontality

All sedimentary and igneous rocks are deposited/flow horizontally, if you see sedimentary rocks that are not horizontal, a tectonic event occurred after the rock formed

explain cross-cutting relationships

Geologic features that cut through rock must have formed after the rocks they cut through

What does the term pre-Cambrian refer to

The Hadean, Archean, and Proterozoic Eons

How did earth form?

formed through the accretion of particles

what is planetary accretion

the process by which small particles in space come together under gravitational forces to form larger bodies

How old is the earth

4.55 Ga

What are the 3 sources of Earth’s internal heat/energy?

1. The formation of the earth through the accretion

2. gravitational contraction as the earth grew

3. radioactive decay of elements

What is planetary differentiation?

The process by which a planetary body develops internal layers. Generated by density differences of material

How did the moon form?

After differentiation, Earth smashed by a mars sized object

4.4 Ga old zircons were discovered in Australia. What did they zircons suggest about the crust during the Hadean?

continental crust existed 4.4 billion years ago.

How would you describe Earth’s atmosphere during the Hadean?

Earth cools down and we get our first continental and stable oceanic crusts. it starts to rain and we have first oceans. Ocean water is very acidic because of carbon dioxide

What was the Late Heavy Bombardment and when did it occur?

end of Hadean, asteroids and comets collide with the earth and destroy any early continental masses

What was the first form of life on Earth?

Bacteria

What is cyanobacteria?

photosythetic bascteria, one of the first life forms and causes the great oxygenation

What are stromatolites?

Mounds of cyannobacteria

Describe, in detail how the continents formed, as discussed in class.

small stable masses of continental crust were generated at subduction zones as volcanic arcs. Eventually, the buoyant, continental masses collided and accreted. During the Archean and Proterozoic, the smaller masses collide together to become larger masses

What is a craton?

Old, cold, stable portion of a continent

What is a platform?

Portion of the continent where the craton is coved by a thick sequence of of younger sedimentary rock layers

What is a shield?

Portion of the continent where the craton is exposed

Did plate tectonics begin in the Archean?

Yes, but plates were much smaller motion of plates occurred much faster b/c the mantle was hotter

Describe the Great Oxygenation Event: how did Earth’s atmosphere become oxygenated?

photosynthesis by cyanobacteria oxygenates the water, oxygen escapes into the atmosphere

What are Banded Iron Formations?

Rocks that formed as the Earth's atmosphere became oxygen-rich.

How do banded iron formations form?

Oxygen in oceans react with iron to produce solid iron-oxide, which sinks and generates the black layers

What is banded iron formations' geologic importance?

They serve as evidence for the Great Oxygenation Event

What was Snowball Earth?

End of the Proterozoic experienced intense, global glaciation, Oceans were covered in sea ice, land was covered in glaciers

What could have cause Snowball Earth to “melt?”

Volcanic eruptions released carbon dioxide into the atmosphere, warming the planet.

What was the name of the supercontinent that formed during the Proterozoic?

Rodinia

Describe the Grenville Orogeny: when did it occur (what Eon)?

occurred when North America collided with South America as part of the assemblage of Rodinia during the Proterozoic

What is the Ediacaran fauna? What kind or organisms were fossilized?

invertebrates resembling worms and jellyfish, These organisms were soft bodied and had a low preservation potential. Many of these organisms are unlike any modern-day organism

How was the Ediacaran Fauna revolutionary?

The organisms suggested that complex, multicellular life existed before the Cambrian Explosion.

What was the Cambrian Explosion?

Rapid diversification of life

what were the four major continental landmasses that formed after the rifting of Rodinia?

Gondwana, Laurentia, Baltica, Siberia

Where, on the globe, was Laurentia located during most of the Paleozoic?

North America

What are the three orogenic events responsible for the development of the Appalachian Mountains?

Alleghanian Orogeny, Taconic Orogeny, Acadian/Caledonian Orogeny

When did the Alleghanian Orogeny occur?

Late-Paleozoic

what occurred to produce the mountains in the Alleghanian Orogeny

North America and Africa collide

When did the Taconic orogeny occur?

Early-Paleozoic

what occurred to produce the mountains in the Taconic Orogeny

A volcanic island arc collides with North America

when did the Acadian/Caledonian Orogeny occur?

Mid-Paleozoic

what occurred to produce the mountains in the Acadian/Caledonian Orogeny

A microcontinent collides with North America.

What was the Antler Orogeny?

faulting along the western edge of laurentia

When and where did the antler orogeny occur?

NW laurentia, Late devonian

When did the first amphibians evolve (Early, Mid, or Late Paleozoic)?

Mid-Paleozoic

What kind of organism was Tiktaalik?

It is a transition organism representing and evolutionary link between fish and the first tetrapods/amphibians

When did the first land plants evolve (Early, Mid, or Late Paleozoic)?

Early Paleozoic

Were the first land plants flower-producing, seed-producing, or spore-producing?

Spore-producing

When did the first amniotes evolve (Early, Mid, or Late Paleozoic)?

Late Paleozoic

What is an amniote?

Organism that lay eggs

Why was amniotes evolution important?

The amniote egg permitted reproduction away from water.

What are the two groups of amniotes?

Reptiles and Synapsids

What type of depositional environment, present on Laurentia during the Late Paleozoic, resulted in vase coal deposits in North America?

sedimentary, swamps

How did life trigger cooler climates during the Late Paleozoic?

plants are abundant and consume carbon dioxide

What was Pangea and when did it form? (Early, Mid, or Late Paleozoic)?

supercontinent, late paleozoic

Describe the end-Permian mass extinction: describe the scope of its size and what may have triggered the extinction event?

Large-scale volcanic eruptions in Siberia.

Describe the three stages of continental rifting?

Fractures form in continental crust, RIft zone widens, and ends when sea-floor spreading begins

Describe the break-up of Pangea: When did it start? Which continental masses separated first?

began during the Mesozoic with the separation of North America and Africa

Describe sea-floor spreading rates during the Cretaceous. How did this contribute to sea-level rise?

During the Cretaceous, sea-floor spreading rates were

higher than today's rates. which changed the size and shape of ocean basins. creating a high sea level

What was the Western Interior Seaway?

was a water body that inundated North America during the Cretaceous

What kind of plate tectonic boundary dominated the west coast of North America during the Mesozoic?

convergent with subduction zones

What were pterosaurs? (Were they dinosaurs? When did pterosaurs reach their evolutionary peak?)

Not dinosaurs. Pterosaurs reached their evolutionary peak during the Cretaceous.

How are dinosaurs different from other reptiles?

Vertical limbs support the body, Legs are positioned beneath their bodies, specialization of the ankle bones, they bear evidence of warm bloodedness, some species had feathers

Who was John Ostrom and what contributions did he make to the field of dinosaur paleontology?

American vertebrate paleontologist discovered Deinonychus, suggested that dinosaurs may have been warm-blooded

What are the two groups of dinosaur and how are these two groups “defined?”

Ornithischians and Saurischian, which are based upon the orientation of the pelvic bones. saurischian points down and orn points back

What is the Hells Creek Formation? (What kind of depositional environment does it represent? What is it contribution to the field of dinosaur paleontology?)

a fluvial system on shores of the Western Interior Seaway. Tyrannosaurs Rex and Triceratops were preserved here.

What was Archaeopteryx and why is it important?

It is a organism that represents the evolutionary transition between birds and dinosaurs.

When did mammals and flowering plants make their debut?

Mesozoic

By end of the Mesozoic, which type of plants were dominant in terms of diversity and distribution? Seed-bearing, spore-bearing, or flower-producing?

flower-producing

What are the two major hypothesis that help explain the mass-extinction event at the end of the Mesozoic?

Large volcanic eruptions in India may have caused significant changes to the climate, triggering a mass extinction. or an asteroid struck Earth at the end of the Mesozoic

What is the evidence that supports the occurrence of an asteroid impact at the end of the Cretaceous.

1. Thin layer of iridium-rich clay

2. Shocked” quartz found in the clay near the impact site

3. Tektites found the clay near the impact site.

4. Impact crater discovered in 1980

What were the final stages of Pangea’s break-up during this the Cenozoic?

Antarctica and Australia break up, Atlantic continues to widen, Greenland separates from Europe

Where did the Laramide and Sevier Orogenies occur (which coast line of which continent).

N. America

How were the Laramide and Sevier Orogenies different? (hint: review subduction angles)

Sevier had steep subduction and laramide had shallow subduction

What was the Farallon Plate? What happened to it and what is left of it?

An ancient Tectonic plate composed of oceanic Lithosphere. In the past, it interacted with the North American plate and the pacific plate. There are only two remnants left: The modern Cocos plate and the Juan deFuca plate

Discuss how the San Andreas Fault system developed.

it developed with the subduction of the farallon plate

What is the Basin and Range Province of North America?

Where is the Basin and range province of North America located

SW America

What kind of tectonic environment is responsible for the basin and range province of North America

continental rifting

What triggered global cooling in the cenozoic

what trigged Ice House conditions in the cenozoic?

What major climate event occurred from 2.5Ma-12,000years (during the Pleistocene)?

Isthmus of Panama

What are some of the distinct skeletal characteristics of mammals?

lower jaw is composed of a single bone, Differentiated teeth, 3 ear bones, 7 neck vertebra, Large brain case, secondary palate that separates the mouth and nasal cavities.

How do paleontologists track the evolution of horses?

fossil record is rich

What is does the term “Anthropocene” represent?

now living in a time when the global environment is shaped by humankind rather than vice versa. Humans have significantly altered Earth’s land surface, oceans, rivers, atmosphere, flora, and fauna.

Where (at what moment in time?) did the Anthropocene Working Group want to place the boundary between the Holocene and Anthropocene? What was significant about this portion of time?

1952, caused it to be heavily rejected because it is too short and humans have impacted earth before then

What location did Anthropocene Working Group identify as the best place to study the Holocene-Anthropocene boundary?

crawford lake, ontario

Why did the Subcommission on Quaternary Stratigraphy reject the “Anthropocene” as a new epoch of the Quaternary?

too short to be an epoch