unit 4 1-50 test 51-55 quiz 6 56-60 quiz 7

Question 1

what is the diameter of the earth?

Answer 1

8,000 miles

Question 2

what is the diameter of the sun?

Answer 2

800,000 miles

Question 3

what is earths circumference?

Answer 3

24,000 miles

Question 4

describe earths three distinct, concentric layers

Answer 4

iron core is larger than 1/2 of earths diameter
mantle composed of ultramafic rocks and minerals
two types of earth crust
oceanic mafic crust (basalt)
continental felsic crust (granitic)

Question 5

what two types of crust does the earth have?

Answer 5

oceanic mafic crust (basalt)

continental felsic crust (granitic)

Question 6

describe the three sources of earths residual heat?

Answer 6

heat from gravitational energy
heat derived from kinetic energy generated by planetesimal collisions
heat generated from later meteor impacts (4.6-3.8 billion years)

Question 7

heat from within the earth is continually generated by

Answer 7

radioactive decay
with melting metallic iron and nickel sank to the center of the earth to form the iron core (iron catastrophe)
the remaining melt was composed of mafic or basaltic rocks that surround the ultramafic earths mantle

Question 8

what is a lithosphere and where is it located?

Answer 8

rigid outer layer containing crust and a frozen part of the upper mantle

Question 9

what is the asthenosphere and where is it located?

Answer 9

partially melted upper mantle that has plastic-like properties

Question 10

describe the lower mantle and where is it located?

Answer 10

(sometimes called the mesosphere) solid layer of rocks between the asthenosphere and iron core

Question 11

describe the components of earths core and where are they located

Answer 11

liquid iron core molten iron with some nickel and rocks (half diameter of earth)
solid iron core +6,000 degrees celceus

Question 12

what happened to most of the hydrogen and helium that accumulated with earths mass?

Answer 12

most of it escaped from earth because earth did not have enough gravity to hold these elements within its atmosphere

Question 13

how much free oxygen was available very early in earths history?

Answer 13

there was almost no free oxygen with earths original atmosphere

Question 14

what does the presence of pyrite grains in early sedimentary rocks imply?

Answer 14

proof that there was no free oxygen cause they didn

Question 15

describe the occurrence of banded iron formations during early times(2.5-2.0 billion years)

Answer 15

having more generated free oxygen the banded iron formations (that require abundant oxygen) became thick and cover vast areas. by this time, free oxygen consumed all the dissolved iron in the oceans

Question 16

which ancient life forms were present at least 3.5 billion years ago that began creating earths free oxygen?

Answer 16

ancient bacteria and algae these life forms used photosynthesis to combine co2 and water into organic molecules and release free oxygen as a waste product into the atmosphere

Question 17

what is the approximate percentage composition of earths atmosphere today?

Answer 17

approximately 78% nitrogen and 21% oxygen (rounded 80%-20%)

Question 18

what happened to most of the co2 that was present in early earths atmosphere?

Answer 18

a small fraction of co2 was converted into oxygen
seawater absorbs co2 from the atmosphere
because of limestone we have very little co2 in our atmosphere

Question 19

how long did it take earths oceans to reach its current salinity levels?

Answer 19

as early as the oceans formed 3.5 to 4.4 billion years

Question 20

alfred wegener was famous for proposing which scientific theory?

Answer 20

continental drift theory in 1915

Question 21

what was pangaea.

Answer 21

the last known super-continent in which all the present-day continents did not stay in the same area over geologic time.

Question 22

remember that wegener used fossils, striations and age of rocks to prove continental drift?

Answer 22

a super continent model because
similarities in shoreline of continents
dist\tinctive rock formations on matching continents
distinctive matching fossil groups

Question 23

why was the theory of continental drift rejected?

Answer 23

he could not provide a mechanism to move the continents

Question 24

what is the current theory about the creation of earths magnetic field?

Answer 24

creates a huge magnetic shield that prevents the earth from being blasted by cosmic particles from the sun

Question 25

what evidence do we have for earths magnetic shield?

Answer 25

the aurora borealis is evidence of earths magnetic shield

Question 26

describes what happens to a magnetite grain when it cools within a basaltic magma.

Answer 26

the grains align themselves to earths magnetic field that is present at that time

Question 27

define paleomagnetism and why is it an important geologic tool.

Answer 27

the study of magnetic fields, as preserved in the magnetic properties of rocks magnetic fields that are preserved in ancient lava flows can be used to demonstrate that earths continents have moved over time

Question 28

who proposed the theory of seafloor spreading?

Answer 28

dr. h. h. hess (1906-1969) in 1960 his theory of sea floor spreading as a method to move and separate the continents

Question 29

magnetic polarity stripes (magnetic reversals) are__ on both sides of the mid-oceanic ridge.

Answer 29

identical polarity stripe on both sides of the ridge thus they are symmetrical on each side of the oceanic ridge

Question 30

what is the name of the deepest submarine trench?

Answer 30

mariana trench more than 36,000 feet depth (about 7 miles)

Question 31

compare the age of basalt at the oceanic ridge to its age at the edge far from the ridge

Answer 31

it becomes older on both sides of the ridge as one moves away from the ridge toward the continents

Question 32

what is a tectonic plate?

Answer 32

a single block of lithosphere that moves about the earths surface plates are outlined by ridges, trenches and mountains individual tectonic plates are based on structural features, not on continents and oceans

Question 33

describe a divergent plate boundary, including the movement of neighboring plates.

Answer 33

mid oceanic ridge also called a spreading center or central rift zone divergent zones are located within the ocean floor where of sea-floor spreading basalt is creating new oceanic crust plates are being moved apart or away from each other (tension) where vertical injections of basalt fill the fracture zones.

Question 34

describe a transform plate boundary, including the movement of neighboring plates?

Answer 34

sliding plate boundary plates slide past one another these are directly associated with divergent zones. the san andreas fault is a transform fault

Question 35

describe a convergent plate bouddary, including the movement of neighboring plates?

Answer 35

subduction zones this area is where the plates comes together(compression) these zones are where continental crust is created most metamorphic rocks are created here. plate motions are complex involving geometry of a curved plate moving on a sphere

Question 36

which tectonic zone can create an ocean basin?

Answer 36

divergent plate boundary | divergent zones

Question 37

where tectonically are all black smokers located?

Answer 37

divergent zones mid oceanic ridge that rises high above the ocean floor hot water escapes in fountains along these zones

Question 38

what do we call a divergent zone on land?

Answer 38

rift (zone) valley

Question 39

what are the three types of convergent zones?

Answer 39

two oceanic crusts meet making volcanic mountains called island arc oceanic crust is subducted creates mountains two continental crusts collide creating gigantic mountains

Question 40

define a subduction zone.

Answer 40

a locality where oceanic crust is being pushed or subducted into the mantle (directly associated with deep-sea trenches or convergent zones)

Question 41

where tectonically are the deep sea trenches located?

Answer 41

subduction zone

Question 42

what is the most favored theory or mechanism today for plate tectonic movements?

Answer 42

slab pull theory weight of the slab entering the mantle will pull the crust remaining into the mantle

Question 43

give an example of a landmass created by a mantle plume or hotspot?

Answer 43

magma that rises from deep inside the mantle, with a continuous supply of magma that may last for 100 million years, even as the overlying plate moves hawaii is the result of a mantle plume or hotspot

Question 44

describe a super-continent cycle and who came up with the name?

Answer 44

about every 500 million years, most of earths continents collide together, then later split apart j. tuzo wilson

Question 45

how is science different from other fields of human endeavor?

Answer 45

science searches for regularities and patterns in the natural world.

Question 46

why is it that many aspects of being human are not amenable to scientific description?

Answer 46

because of culture and opinion

Question 47

which subjective sciences are not normally addressed by normal science?

Answer 47

justice and honor that varies by culture-not science | esthetics and manners, etc. - these vary by culture and not by science

Question 48

questions that science can address are limited by___?

Answer 48

the properties of the natural world the instruments available to extend human sense socially imposed missions the paradigm that guide scientific inquiry

Question 49

how absolute is scientific knowledge?

Answer 49

is not absolute is tentative, approximate and subject to revision also applies to the earth sciences

Question 50

with many publicized articles about global warming, should they also give reasons that do not fit the model?

Answer 50

yes they should

Question 51

what name did edward suess propose for a super-continent in 1885?

Answer 51

gondwanaland or gondwana

Question 52

the picture on page 31 figure 2.5 shows lines of glacial movement. what are these lines

Answer 52

striations | glacial striations scratch marks

Question 53

the temperature at which magnetite can gain or loses it remnant magnetism from heating?

Answer 53

curie point

Question 54

as a group how many geologists accept that plates are created at oceanic ridges and destroyed at deep sea trenches?

Answer 54

most

Question 55

the lithosphere overlies the hotter and weaker semi-plastic?

Answer 55

asthenosphere

Question 56

the eoarchean era ended ____ago.

Answer 56

3.6 billion years

Question 57

this figure is illustrating the origin of ______

Answer 57

granitic continental crust | the first protocontinents formed

Question 58

the archean eon alone accounts for____of all geologic time.

Answer 58

32.6%

Question 59

the approximate age of the oldest detrital zircons in australia

Answer 59

4.4 billion years old

Question 60

how many named greenstone belts are in figure 19.9

Answer 60

5