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earth history > unit5 1-54 test 55-59 quiz 8 60-64 quiz 9 > Flashcards

unit5 1-54 test 55-59 quiz 8 60-64 quiz 9 Flashcards

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1
Q

how do we use the name precambrian?

A

informal name for the earliest chapter in earths history

refers to all rocks beneath cambrian-aged rocks, and to all time before the cambrian period

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2
Q

which range of earths history is represented by the precambrian, in by (billions of years)?

A

+4.6 billion years ago and ended 542 million years ago or 4.0 billion years

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3
Q

which two rock types represents most of the precambrian outcrop surfaces?

A

igneous and metamorphic rocks

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4
Q

what type of fossil is most representative of the precambrian?

A

single-cell organisms

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5
Q

where is found the largest north american precambrian exposure?

A

around the hudson bay, canada

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6
Q

where can we find exposures of precambrian rocks in texas?

A

llano area, central tx, carrizo mt. near van horn, tx and the franklin mts. at el paso, tx

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7
Q

how do we use the term basement rocks?

A

usual name for precambrian rocks

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8
Q

define a (precambrian) shield

A

exposed portion of the basement of a continent that is composed of precambrian rocks

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9
Q

define a platform

A

buried or covered surfaces of a shield

forms the foundation upon which other sediments are deposited

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10
Q

define a craton

A

the nucleus of a continent made up of a shield and a platform
crraons are not composed of uniform series of rock types.

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11
Q

what is the canadian shield?

A

the exposed portion of the north american craton

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12
Q

what are the only representative rocks for the very beginning of the hadean eon?

A

meteorites

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13
Q

what is earths oldest particle known and its age in by?

A

4,404 billion years, one zircon crystal represents the oldest particle on planet earth

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14
Q

what time period (by) is represent by the archean eon?

A

period of 4.0 billion years to 2.5 billion years

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15
Q

which country do we find earths oldest crustal rocks?

A

in northern canada the acasta gneiss

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16
Q

describe the effect of the moon on earths surface and oceans during the early archean eon.

A

the moon was much closer then, causing the earths crust to rise and fall by 200 feet every day
the oceans were getting deeper but were subjected to 1,000 foot tides

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17
Q

when did a large number of meteorites stop pelting the earth?

A

3.8 billion years

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18
Q

what type of tectonic feature can create continental crust?

A

convergent- subduction zones
oceanic crust being subducted under oceanic crust, island arcs that create continental crust (geologic province)are created

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19
Q

describe the rocks surrounding a typical precambrian geologic province.

A

surrounded by metamorphic rocks

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20
Q

what is graywacke sandstone and what type of environment would it represent?

A

a sandstone that shows a decrease in grain size from the bottom to the top of the bed and composed of abundant clay and volcanic rock fragments
they form in deep waters either beyond a continental shelf or off an oceanic island

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21
Q

what is a greenstone?

A

former volcanic and sedimentary rocks that are rich in chlorite

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22
Q

what do greenstone belts represent?

A

zones of rocks rich in chlorite

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23
Q

where do we find united states oldest crustal rocks and what is the formation name?

A

minesota river valley called the morton gneiss dated 3.5 billion years

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24
Q

at what period of time was earths first ice age (by)?

A

the beginning of the early proterozoic (2.7-2.5 BY)

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25
Q

what is a tillite? sometimes it is also called a __.

A

sedimentary deposits that include rocks and boulders from icebergs
also called drop-stones

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26
Q

how do we subdivide the proterozoic eon (using modifiers)?

A

early, middle, and late proterozoic times (2.5 by to 1.6 by)

27
Q

what are banded iron formations?

A

alternating layers of iron oxides and chert deposited in the sea (chert is a type of quartz)

28
Q

why do we no longer find BIF after 2.0 BY?

A

after 2.0 by there would be so much free oxygen about 1% that very minor dissolved iron would reach the ocean and there would be no more thick deposits of bif

29
Q

what tectonic event occurred near missouri during the middle proterozoic eon?

A

mid-continental rift north america began ripping apart

30
Q

what mineral resources do the keweenawan basalts contain?

A

enormous amounts of copper metal and silver metal

31
Q

which supercontinent was created with the grenville province?

A

the first supercontinent rodinia 1.3-1.0 billion years

32
Q

how long was a typical day during the middle proterozoic?

A

it slowed down from an 8 hour day to an 18.2 hour day or 480 day year

33
Q

what famous texas feature was created with the grenville province?

A

enchanted rock a granite mass part of the 1.2 by grenville province located in central texas (llano area)

34
Q

what is the snowball earth theory?

A

a time when the entire earth was covered with ice

35
Q

which super continent was created during the late proterozoic eon?

A

supercontinent pannotia 650 million years

36
Q

all living matter is composed of at least four elements; what are the elements?

A

carbon, hydrogen, oxygen, and nitrogen

37
Q

what is s.e.t.l?

A

search for extra-terrestrial intelligence

38
Q

what would be a primordial soup?

A

organic compounds, formed by a variety of processes, from molecules that accumulate in the shallow oceans

39
Q

what is a microsphere?

A

simple organic molecules that show great organizational complexity

40
Q

how often has man been able to create life from chemicals?

A

man has never been able to create life

41
Q

what was miller able to create?

A

1953 he was able to create all 20 amino acids, using only methane, ammonia, water, hydrogen gas and a spark of electricity in a glass apparatus

42
Q

what is meant by chemical fossils?

A

fossil life detected by using non-radioactive isotopes of 12c/13c from “carbon films”

43
Q

what is the difference between an autotroph and a heterotroph?

A

autotroph an organism that produces food inorganically

heterotrophic organism that must consume organic molecules for survival (must eat other forms of live or dead organisms)

44
Q

what is cyanobacteria?

A

aquatic bacteria that uses photosynthesis

contributor to the origin of plants

45
Q

in what type of rock are most very early precambrian fossils found(hint; chert)

A

most are found in black chert

46
Q

what is the approximate age (by) of some of the oldest body fossils found?

A

filaments of cyanobacteria aged at 3.465 by in the warrawoona group in australia (before the first 2.5 by ice age)

47
Q

what are stromatolites?

A

cyanobacteria and other bacteria that form colonial associations
mound-like structures consisting of laminated carbonate rock produced by trapping of sediments by groups of organisms (cyanobacteria)

48
Q

what are eukaryotes?

A

are important in that they have more advanced cells than bacteria
earliest are single-celled organisms they are larger than prokaryote cells
cells have a nucleus and prokaryotes do not

49
Q

why are arcitarchs?

A

are cysts of algae. in time of drought alge will create a cellular wall called a cyst to protect itself

50
Q

based on the fossil record, what represents the oldest known multicellular organism?

A

multicellular alge in michigan 2.1.billion years

51
Q

what are metazoans?

A

multicellular animals

52
Q

what type of fossil evidence do we have for very old metazoans?

A

animal burrows aged at 1.2 by have been found in australia and west texas (during rodinia)

53
Q

what are ediacaran fossils? (hard/soft; predator/prey; jaws/absorbing, etc.)

A

soft-bodied animals no jaws and there were no predators

54
Q

describe the climatic environment where ediacaran organisms lived.

A

shallow, cold water marine environments, between 760my-520my

55
Q

archean and proterozoic rocks have yielded more than __ of the worlds gold

A

50%

56
Q

archean rocks have yielded almost__of the worlds chrome deposits.

A

1/4

57
Q

the major source of iron ores that is present on all continents is __

A

branded iron formations

58
Q

economically recoverable oil and natural gas in proterozoic rocks occur in___

A

china and siberia midcontinent rift

59
Q

the archean plates may have moved faster than today because earth possessed____

A

more radiogenic heat

60
Q

what are mobile belts?

A

are elongated areas of mountain-building activity. they are lcated along the margins of continents where sediments are deposited in the relatively shallow waters of the continental shelf and the deeper waters at the base of the continental slope

61
Q

in the paleozoic, florida was part of the continent___

A

gondwana

62
Q

in the beginning of the paleozoic, how many continents were there?

A

6 major

63
Q

during the late cambrian, china was located

A

at low tropical latitudes

64
Q

what was the name of the giant ocean at this time?

A

panthalassa

earth history (7 decks)

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