Geo Exam- Test 3

What is the Big Bang Theory?

The idea that 15 billion years ago there was only energy in the universe no mass

What are the four forces that govern the universe?

Gravity- interaction of masses
Electromagnetic interaction (binds atoms to form molecules)
Strong nuclear interaction- binds protons and neutrons
Weak nuclear interaction- radioactive decay

Does every mass have a gravitational attraction to every other mass?

Yes

How did Solar Nebula form?

Forces of mass are attracted by gravity and the idea is that the nebula starts to rotate and as it rotates most of the most of the mass is in the center but aggregates of mass are out there in the nebula and will ultimately form planets

How do planetesimals coalesce to form planets?

via gravity

What is the sun mostly doing

hydrogen undergoing nuclear fusion to form helium- opposite of radioactive decay

How did the moon form?

Theia- a proto planet- collided with earth and threw up a lot of material, this mass went into orbit around the earth and coalesced to form the moon

How long ago did the earth form?

2.5 billion years ago

Did rocks exist during the Hadean (Early Eoarchean)

No

When did the Hadean (early Eoarchean ) begin?

4.5 billion years ago but there is nothing to radio metrically age date to verify that

What happened to the earth in the hadean?

the earth accreted from planetesimals and differentiated into core, mantle, and some crust

When must have rocks began exisiting? How do we know?

Rocks must have started existing by the end of the late Hadean, we now from rocks with zicrons- formed in igneous rocks- old enough to be from hadean, these rocks were found in Jackhills Australia

What can be evidenced in the Archean?

Rocks, first evidence of oceans, DNA- because we start to see fossil evidence of bacteria prokaryotes, tectonic activity, and the first continent was formed.

Was volcanism going on in the Archean?

yes, lots of itW

What are the cores of Continents called?

Cratons:
Shield- Areas of exposed Precambrian rock
Platform- Precambrian rock covered by sedimentary rocks

Where did most greenstone belts occur in north america during the Arcehan?

the Superior and Slave cratons of the Canadian Shield

What type of life did the Archean Have?

Inside Chert's are Cyanophytes- bacterica that can make their own
food- what make stromatolites today

What was the environment/ atmosphere in the Archean?

Degassing was occuring- no oxygen in the atmosphere early on gasses like Hydrogen, water, Carbon Dioxide, Nitrogen, and water came out of lava and volcanic stuff but not a lot of oxygen
Comets- may have brought in some stuff for atmosphere as well

How did the earth get Oxygen- Archean

Photochemical dissociation of Water- not a lot of oxygen production
Photosynthesis- Taking CO2 which we can get out of degassing of volcanos and adding water in the presence of light creating Glucose and excess oxygen which is released into the atmosphere

By the end of the Archean what percentage level did the earth have of oxygen?

1% level of Oxygen today

When was the Proterozoic

From 2.5 Billion to 41 Million years ago

Was there an increase or decrease of Oxygen during the Proterozoic?

There was a slight decrease

When did we start seeing Eukaryotic organisms- multicellular?

Durign the Proterozoic

What happened to the the atmosphere during the Proterozoic?

enough oxygen in the atmosphere to stabilize the ozone

When do we start to see a lot of fossils in rocks?

in 542 million or Cambrian

Why do we separate Archean and Proterozoic?

there was a shift in mechanics of tectonic activity
we started seeing ophiolites-when subduction happens and the rocks get caught in the mantle- in the record telling us they were working the same as today

When was the Laurentia (creton) forming to make North America?

During the Proterozoic

How did the North America we know begin to form?

mini creatons banged into each other and coalesed to form North America during the Proterozoic

How many big continents did Proterozic have? what were there names?

Rodinia and Pannotia

What do you see in ophiolite?

basalts, pillow basalts

What is a banded iron formation?

Alternating layers of material- 95% were made during the Paleoproterozoic
red stuff- chert, grey- hematite and magnetite- needed oxygen to be there to form

What happened with the oxygen during the Proterozoic?

we got cyanobacteria and then algae so levels grew to 20% of what we have today

What was the Proterozoic Glaciation?

Glacial deposits seen in differing sizes of grain- sitting on what was then the bed rock- when it melts the rocks sink to the bottom of the lake

What was living during the Proterozoic?

Acritarchs- made of spore pollenen (likely algae spores), multicellular eukaryotes, Amoeba, at end we see Kimbrealla- we say it is a mollusk

What happened to the Continental US during the Cambrian?

Seas covered it- reason there are so many marine fossils- occured mid Cambrian

What island began moving toward America during the Cambrian?

The Tacanic island arc toward the east coast

What was living during the Cambrian?

Mos major groups of animals seen today, first sighting of fish and Chordates, Arthropods- trilobites, Mollusks- clams and brachiopods, Wh

What did organisms eat during the Cambrian?

Plants, mainly Algae

How do you tell a brachipod from a clam?

From left to right it is mirror image.

What might animals have long spines during the Cambrian?

because the sea floor was muddy- so the spine increases surface volume ration making it easier to float and move on the sea floor.

What is the Burgess Shale?

Found in British Columbia- 500 million years old- organisms from Cambrian - most arthoropods and sponges

When was the Ordovician?

After Cambrian- 585 to 444 Million years ago

Where was North America during the Ordovician?

slightly over the equator, even more under water

When does the island arch collide with North America?

In middle Ordovician- starts in Canada

What was the Taconic Orogeny?

the plastering of hte island arch- attached ot Greenville rocks- the NA plate subducted all the shedding clastic material were caught and the rocks metamorphose, the island arch was thrust onto these rocks and these rocks thrust upon the original rock- Green Ville

What life was there during the ordovician?

Solitary Corals- mor dominante during Paleozoic,
Traliobites- diversify
Crynoids
Large mollusks
snails
Eurypterid-diverse, highest predators (arthropod)
Brachiopods- diversify abundant in marine environment
Echinoderm- Crinoid- more diverse, many live attached ot substrate
mollusk- cephalopod- more diverse- clams, gastropods
Hemichordate- has nerve running down the center
Bryozoan

What does a heaped Crinoid Meadow show?

that there was a catastrophic event - like a big storm bringing sediment

What was the Ordovician- Silurian Extinction Event

we don't know what casued it- but it is one of the important extinction events shaping the organisms that survived and became diverse after
Extinct:
Many Trilobites
Brachiopods
Bryozoans
NONE ARE COMPLETELY EXTINCT

What times were a part of the Paleozoic?

Ordovicion, Cambrian, Proterozoic,

What were tectonic like during the early Ordovicion?

There wasa volcanic arc off the side of North America
we had half of Virginia- most of US and Canada under marine
causing lots of limestone production
Late Ordovicion- island arcs have collided with eastern US- adding from east to blue ridge on VA
Erosion on both east and west side

What happens to the US during the Silurian?

Most of it is under water

What was Genglana during Silurian?

everything except for BalticaW

What was life like during the Silurian?

Triolobite, gossan corals (soiltary and colonia), molluscs (Sephlapod mollusk), eurytherites- arthropod
Much of what is in the oceans was ther
Snails
Cephalopod Mollusks- lines will be chambers

When did snails come into existence?

During the Cambrian

Brachiopods Druing Silurian

They diversify,
Clam or Brach- brach has bilateral symmetry

Crinoids- Echinoderm- Sillurian

thrive, lots of mass death events E

Eurypterid- Sillurian

Where thereW

When are fish first found?

Silurian- most had no jaws , Jawed ones called Placoderms heads were armored with bony plates competed with eurypterid to be apex predator

Silurian- did lobe-finned fish have jaws

yes

How many classes of silurian fish survive today?

5

When did plants go to land?

During Silurian, from chlorophytes or green algae- seeming stem plants for all higher plants that have chlorophile, only spore bearing plants