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

Question 1

how do we use the name precambrian?

Answer 1

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

Question 2

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

Answer 2

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

Question 3

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

Answer 3

igneous and metamorphic rocks

Question 4

what type of fossil is most representative of the precambrian?

Answer 4

single-cell organisms

Question 5

where is found the largest north american precambrian exposure?

Answer 5

around the hudson bay, canada

Question 6

where can we find exposures of precambrian rocks in texas?

Answer 6

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

Question 7

how do we use the term basement rocks?

Answer 7

usual name for precambrian rocks

Question 8

define a (precambrian) shield

Answer 8

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

Question 9

define a platform

Answer 9

buried or covered surfaces of a shield

forms the foundation upon which other sediments are deposited

Question 10

define a craton

Answer 10

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

Question 11

what is the canadian shield?

Answer 11

the exposed portion of the north american craton

Question 12

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

Answer 12

meteorites

Question 13

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

Answer 13

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

Question 14

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

Answer 14

period of 4.0 billion years to 2.5 billion years

Question 15

which country do we find earths oldest crustal rocks?

Answer 15

in northern canada the acasta gneiss

Question 16

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

Answer 16

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

Question 17

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

Answer 17

3.8 billion years

Question 18

what type of tectonic feature can create continental crust?

Answer 18

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

Question 19

describe the rocks surrounding a typical precambrian geologic province.

Answer 19

surrounded by metamorphic rocks

Question 20

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

Answer 20

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

Question 21

what is a greenstone?

Answer 21

former volcanic and sedimentary rocks that are rich in chlorite

Question 22

what do greenstone belts represent?

Answer 22

zones of rocks rich in chlorite

Question 23

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

Answer 23

minesota river valley called the morton gneiss dated 3.5 billion years

Question 24

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

Answer 24

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

Question 25

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

Answer 25

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

Question 26

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

Answer 26

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

Question 27

what are banded iron formations?

Answer 27

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

Question 28

why do we no longer find BIF after 2.0 BY?

Answer 28

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

Question 29

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

Answer 29

mid-continental rift north america began ripping apart

Question 30

what mineral resources do the keweenawan basalts contain?

Answer 30

enormous amounts of copper metal and silver metal

Question 31

which supercontinent was created with the grenville province?

Answer 31

the first supercontinent rodinia 1.3-1.0 billion years

Question 32

how long was a typical day during the middle proterozoic?

Answer 32

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

Question 33

what famous texas feature was created with the grenville province?

Answer 33

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

Question 34

what is the snowball earth theory?

Answer 34

a time when the entire earth was covered with ice

Question 35

which super continent was created during the late proterozoic eon?

Answer 35

supercontinent pannotia 650 million years

Question 36

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

Answer 36

carbon, hydrogen, oxygen, and nitrogen

Question 37

what is s.e.t.l?

Answer 37

search for extra-terrestrial intelligence

Question 38

what would be a primordial soup?

Answer 38

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

Question 39

what is a microsphere?

Answer 39

simple organic molecules that show great organizational complexity

Question 40

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

Answer 40

man has never been able to create life

Question 41

what was miller able to create?

Answer 41

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

Question 42

what is meant by chemical fossils?

Answer 42

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

Question 43

what is the difference between an autotroph and a heterotroph?

Answer 43

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)

Question 44

what is cyanobacteria?

Answer 44

aquatic bacteria that uses photosynthesis | contributor to the origin of plants

Question 45

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

Answer 45

most are found in black chert

Question 46

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

Answer 46

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

Question 47

what are stromatolites?

Answer 47

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)

Question 48

what are eukaryotes?

Answer 48

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

Question 49

why are arcitarchs?

Answer 49

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

Question 50

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

Answer 50

multicellular alge in michigan 2.1.billion years

Question 51

what are metazoans?

Answer 51

multicellular animals

Question 52

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

Answer 52

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

Question 53

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

Answer 53

soft-bodied animals no jaws and there were no predators

Question 54

describe the climatic environment where ediacaran organisms lived.

Answer 54

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

Question 55

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

Answer 55

50%

Question 56

archean rocks have yielded almost__of the worlds chrome deposits.

Answer 56

1/4

Question 57

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

Answer 57

branded iron formations

Question 58

economically recoverable oil and natural gas in proterozoic rocks occur in___

Answer 58

china and siberia midcontinent rift

Question 59

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

Answer 59

more radiogenic heat

Question 60

what are mobile belts?

Answer 60

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

Question 61

in the paleozoic, florida was part of the continent___

Answer 61

gondwana

Question 62

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

Answer 62

6 major

Question 63

during the late cambrian, china was located

Answer 63

at low tropical latitudes

Question 64

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

Answer 64

panthalassa