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HotE > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

how many ice ages have there been in the last 3 Ga

A

5-6

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2
Q

ice age

A

relatively long period of time where the earths surface temperature and atmospheric temperature are reduces that allow for continental, polar ice sheets and alpine glaciers to grow. within one ice age there are several glacial and interglacial periods

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3
Q

most recent ice age

A

late cenezoic ice age, 34 Ma - present

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4
Q

glacial periods

A

major ice sheets on the continents, lowered sea levels, there was one 20,000 to 25,000 years ago that was the last glacial maximum

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5
Q

interglacial periods

A

restricted ice volumes, raised sea levels, like the present time one that started

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6
Q

how much of the world is covered in ice right now

A

less than 10 %

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7
Q

how much of the world was covered in ice at the last glacial maximm

A

30%

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8
Q

oldest canadian animals

A

ediacaran biota, from the ediacaran period (635 to 539Ma). they are seen in mistaken point, newfoundland, and all the life forms are from 575 to 541 Ma

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9
Q

examples of some ediacaran biota

A

osmotrophs and matground grazers

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10
Q

examples of cambrian fauna

A

trilobite, hyolithis, lingulid brachiopod, eocrinoid

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11
Q

cambrian period

A

541 to 485.4 Ma

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12
Q

walcott Quarry, Burgess shale

A

collapse of the reef top deposited shallow water fauna that were previously higher in muds at the base of the escarpment. the conditions allowed preservation of soft parts (lagerstatte). shale is 508 Ma, well into the cambrian period

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13
Q

cambrain explosion of life

A

started 538.8 Ma. possible causes were increse in oxygen, or increase in carbonate concentration, allowing skeletons to form. all principal animal groups developed between 530 and 520 Ma. shelled forms developed and trace fossils showed complex behaviour.

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14
Q

panarthropods

A

the lobopods and radiodonts (spoke teeth) are now thought to be the stem-ancestors of the arthropods. modern genomics as well as the burgess and similar fossils help understand how tardigrades, onychophorans and arthropods are related

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15
Q

tectonics in cambrain north america

A

a period of tectonic stability with no divergent or convergent boundaries only transform from 538.8 to 485 Ma. divergent margins along the east and west coast. Carbonates, sands deposited in shallow inland seas are found in the ottawa area now

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16
Q

what did the taconic mountains do

A

supplied a lot of sediment inland to the appalachian foreland basin which created the NE

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17
Q

mid-ordovician in north america

A

most of the continent is covered by shallow inland seas - carbonate deposition. erosion of mountains provided source of clastic sediments

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18
Q

epeiric

A

shallow inland seas

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19
Q

queenston clastic wedge

A

thick acumulation of sediment or sedimentary rocks in a lens shape. thin near the mountain fron, thickens landwards, then becomes thinner further inland

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20
Q

niagaran paleozoic stratigraphy

A

queenston clastic wedge is in the NE as queenston shale, whirlpool sandstone, grimsby shale, thorold sandstone.
middle silurian rocks record some mud deposition (shales) and reef formations (limestones and dolomites)

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21
Q

middle silurian in NA

A

input of clastic sediments reduced. depostion of limestones (clear water) and some shales

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22
Q

largest salt mine in the world

A

goderic ontario. in a really ideal spot to reach rocks from the silurian period which are mainly halites and evaporites

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23
Q

paleozoic sedimentary basins

A

paleozoic rocks 800 m thick below hamilton. it thickens westward to michigan basin and eastward to the appalachian basin

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24
Q

structure of paleozoic layer

A

strata gently dips to the SW(less than 1 deg.) because it is a basin. there is a strike NE-SW, younging to the SW. resistant silurian limestones and dolostones form the NE

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25
Q

examples of life in the paleozoic seas.

A

all marine, no life had left it yet. brachiopods, corals, eurypterids, trilobites, cephalopods. these are preserved as fossils not

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26
Q

crinoids (sea lilies)

A

animals attached to the sea floor. arms gather food particles from the water and the stem consists of plates that wall apart when the animal dies. the class crinoidea currently has 700 living species but they were more diverse in the ordovician

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27
Q

cephalopods

A

squid like animal with coiled or straight shell that has an internal chamber. they were carniveroud pelagic organisms. they were like 6ft long

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28
Q

pelagic organims

A

live and swim in water columns, meaning they went from the ocean floor to surface

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29
Q

tabulate corals

A

extinct but related to modern corals. there were 300 species identified. capture small animals with tenticles, and were important reef builders in their time. they were not big, and only a couple cm in diameter.

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30
Q

parts of tabulate corals

A

caralite was the honey comb looking section and tabulae are sheet like structures running lengthwise

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31
Q

eurypterids (sea scorpions)

A

aquatic invertibrates (brackish estuaries). they had nasty pincers that indicate penetration, were up to 3m long, and ordovician (permian)

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32
Q

brachiopods

A

outnumbered trilobites by teh ordovician. bivalve mollusc with asymetrical shells, sesssile bottom dwellers and filter feeders. they were very comon in the Silurian (5,000 genera), are rare in present day (100 genera)

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33
Q

what was rodinia

A

an ancient super continent

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34
Q

phanerozoic sequences

A

rodinia started to break up around 570 Ma, proto-atlantic ocean opens up (laperus ocean) this diversified life

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35
Q

what are mass extinctions

A

episodes of globally significant extinctions where more than 20% of marine life genera goes extinct, and 75% of all species goes extinct.

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36
Q

how many mass extinction events have their been

A

5, all in the phanerozoic

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37
Q

what were the mass extinction names

A

Late ordovician, late devonian, late permian, late triassic, late cretaceous

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38
Q

what needs to be known to figure out mass extinctions

A

when the event occurred, how quickly it occurred, and what other global changes were taking place

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39
Q

late ordovician extinction
- ordovician-Silurian Extinction

A

445-440 Ma. 57% of marine genera disappeared (21 families of trilobites; brachipods, bivalves, corals) and 85% of marine species. probably occured over several million years in two phaes. suspectes cause is glaciation in the sahara that was by the south pole: ice sheets impacted photosynthetic organisms, lower sea levels diminished habitats, and there was a decrease in temp

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40
Q

what period did life move to land

A

in the middle to upper paleozoic (415 to 250 Ma). this began plants and animal life on land

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41
Q

when did life move to land

A

440 - 355 Ma. in the mid paleozoic. This was the mid paleozoic marine revolution.

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42
Q

what happened in the mid-paleozoic marine revolution

A

appearance of new predators - jawed fishes, devonian period (age of the fishes) - placoderms, sharks, rays, lungfish, and coelaccanths, and evolution of amphibians. it was an evolutionary step that lead to 99% of all vertibrates

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43
Q

why were jawed fishes important

A

the nevolution of them brought up a lot of predation, which awarded most vertebrates to thrive

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44
Q

placoderms

A

armoured prehistoric fish with haws but no scales. they had a naked body and fins precursor to limbs

45
Q

sarcopterygii (lobe finned fish)

A

fins resemble limb buds. lobe finned fished became the first vertibrates on land

46
Q

what periods are in the late paleozoic

A

devonian, mississippian/pennsulvanian (Carboniferous), and permian

47
Q

devonian age

A

419 to 359 Ma

48
Q

mississippian age

A

359 to 323 Ma

49
Q

Pennsylvanian age

A

323 to 299 Ma

50
Q

perminian age

A

299 to 252 Ma

51
Q

why were there big plants in the devonian

A

adaptive radiation was underway

52
Q

what did big plants mean

A

higher O2 and lower CO2 emissions

53
Q

ichthyostega

A

“first” animal to walk on land

54
Q

coelacanth

A

living fossil (2 current extant species), over 100 extinct species

55
Q

when did insects arive

A

in the Devonian. dragonfly had up to a 1m wingspan, millipedes were up to 2m long, and there were carboniferous cockroaches. they do not preserve well in fossils though.

56
Q

what were the first animals likely to thrive on land

A

anthropods. they were very large at the time because niches were occupied so they could easily take them over without competition

57
Q

myriapods

A

group that includes centipedes and millipides likely first conquered the land starting in 414 Ma

58
Q

oldest land animal fossil

A

millipede-like from 425 Ma in Scotland

59
Q

when did embryophyta (land plants appear)

A

by the mid-cambrain

60
Q

coal

A

combustible fossil fuel that contains a large amount of carbon-based material. lots of good quality coal comes from the carboniferous. coal needs time and pressure to form

61
Q

what happened with plants in the deconian

A

it marks the begining of extensive land colinization by plants. spore bearing and seed bearing plants, with giant ferns, horsetails up to 7m high

62
Q

peat

A

worst type of coal because lowest carbon content. it is the first step in coal formation. it is the accumulation of decayed vegetation or organic matter.

63
Q

lignite coal

A

low-grade and took almost 250 MA to form. it is brownish and has more moisture and less carbon content, of about 25%

64
Q

bituminous coal

A

bitmus coal takes around 100 to 300 Million years to form under high temp and pressure conditions. it is black and has less moisture and more carbon content (45 to 68%). it is used a lot in thermal power plants and industrial boilers

65
Q

anthracite coal

A

a lusturous black and is the highest quality. it takes over 300 million years to form. has almost no moisture content, and 86 to 97% carbon content. it does not release much soot on burns, making them cleaner and a great application in stoves, furnaces, and filtration systems.

66
Q

joggins, nova scotia

A

coal age galapagos where diverse fossils from the carboniferous can be seen most dating from 318 to 303 Ma. tides from the bay of fundy continously erode and expose new rocks. it is a UNESCO world heritage site and composed of alternating unites of limestone, sandstone, mudstones, carbonaceous shales and coals. it is the coal age galapagos where diverse fossils from carboniferous can be seen.

67
Q

plate tectonic theory

A

earths surface is divided into a series of large plates that move around allowing the continents to change position

68
Q

who and how was plate tectonic theory developed

A

alfred wegener (1912) published ideas on continental drift. he proposed the supercontinent Pangea. he sam similarities in fossils that wouldnt be able to cross the seas on many continents, the pieces fit together like a puzzle, and glacial sedimentation

69
Q

what is a supercontinent

A

composed of most, if not all of earths continental blocks or cratons to form a single large landmass

70
Q

midocean ridges

A

a seafloor mountain system formed by plate tectonics

71
Q

geomagnetism

A

earths magnetc field is a vector quantity, it is constantly changing in strength and direction.

72
Q

how much do the magnetic poles move

A

between 1831 and 2001 thew N magnetic pole moved 1100km. since 19760 the NMP has accelerated and is now moving more than 40km per year and will reach siberia in 50 years if it doesnt change course or slow down

73
Q

how do rocks record magneitc field

A

magnetic minerals (magnetite) are fixed in the rock when it solidifies or lithifies, which is recorded. this can be reset through heating

74
Q

how are magnetic fields in rocks measures

A

magnetometer, in a study called paleomagnetism.

75
Q

anomalies

A

changes in magnetic properties

76
Q

how long have magnetic reversals been documented

A

330 Ma, with the last being 780,000 years ago

77
Q

how long do magnetic reversals take

A

1,000 - 8,000 years

78
Q

testing sea floor spreading

A

they surveyed the ocean floor with magnetometers to identify patterns in anomalies on each side of MOR, which should be identical. the patterns match the pattern of magnetif field reversals. this confirmed the formation of sea floor at MORs and movement away from the ridges in cm/year. this means the age of the sea floor can be preditced.

79
Q

where is the oldest sea floor and how old

A

a stretch of the easters mediterannean sea between cyprus, crete, and egypt called the herodotus basin is 340 Ma

80
Q

important parts of the cambrian

A
  • 541 - 485 Ma
  • complex life emerges
81
Q

important parts of the ordovician-Silurian

A
  • 485 - 419 Ma
  • Niagara excarpment
  • marine life continues to thrive
82
Q

important parts of the devonian

A
  • 419 - 359 Ma
  • age of fishes
  • life starts going to land
83
Q

important parts of the carboniferous

A
  • plant-like propogates
  • coal develops
  • carbon sequestering
  • can be split into mississippian and pennsylvanian
84
Q

what was the paleogeography of earth in the late carboniferous (310 Ma)

A

laurussia has fused with gondwana to form pangea

85
Q

pangea

A

formation started as early as 410 Ma when laurentian, baltican, and acalonian cratons collided to create euramerica. this then collided with gondwana by the lade devonian ealy permian and was completely formed by 250 Ma in the permian. the break up started at 200 Ma

86
Q

wilson cycles

A

a model that describes the opening and closing of ocean basins and the subduction and divergence of tectonic plates during the assembly and disassembly of supercontinents

87
Q

lapetus ocean

A

wilson hypothesized that it once lay between sutures and welded blocks in ENA because of fossils that looked similar on either side of the now atlantic.

88
Q

what did williams do in newfoundland

A

he first identifies 4 major zones, and later extended his maps into mainland canada and USA, and then wester europe

89
Q

4 major zones of Newfoundland

A
  • humber is the ancient
  • laurentian continental margin
  • dunnage and gander are part of the ancient lapetus ocean
  • avalon is the old eastern continent that closed the lapetus ocean when attached
90
Q

precambrian basement of newfoundland

A

characterizes ancient eastern margin of laurentia. basement rocks were covered by shallow water limestones -now carbonates - indicating a passive continental margin that faced east (actually south). these limestonea re interpreted as cambrian-ordovician reefs. found ophilites present

91
Q

ophiolites

A

pieces of oceanic plate that have been thrusted (obducted) onto the edge of the continental plates. they are mafic in nature

92
Q

table mountains

A

were siliva-poor magnesium rocks (olivine rich) that inhibit vegetation

93
Q

what resulted from ophiolite sequences

A

sheeted dikes and pillow basalt now present

94
Q

evolution of table mountain

A

the ophalites originated as oceanic crust, and were later thrust onto the eastern margin(laurentia) as lapetus closed.

95
Q

out-of place origin

A

allocthonous

96
Q

in-place origin

A

autocthonous

97
Q

what creates extensional sedimentary basins

A

rifts and passive margins

98
Q

what creates compressive sedimentary basins

A

trenches and foreland basins

99
Q

sedimentary response

A

east facing passive margin carbonate and shallow marine facies are overlain by westerly derived deep water deposits. eventually as compression continues, deep water facies are overlain by fluvio-deltaic deposits. tilted shales and sandstones are deformed easterly derived deep water sediments. the ocean originally lay to the east, now there is evidence of uplifted areas that were eroded to form deep water sediments. these are deposited over old carbonares

100
Q

how did graded beds and ripples form

A

by waning turbidity currents in deep water

101
Q

catskill mountains, pennsylvania

A

zig-zag pattern indicates folds due to compression that formed pangeo, 300 Ma

102
Q

formation of pangea

A

paleozoic tectonic evolution records the closing of a number of oceans during the assembly of pangeo. phases of compression as terranes accrete define named orogenies taconic, acadian, alleghanian

103
Q

when was the rifting of rodinia and the creation of lapetus

A

750 Ma, in the neoproterozoic

104
Q

when had the lapetus ocean formed by

A

540 Ma, in the cambrian

105
Q

when was the taconic orogeny

A

450 Ma, in the ordovician

106
Q

when was the acadian orogeny

A

350 Ma, in the carboniferous

107
Q

when was pangeo formed

A

260-250 Ma, in the permian

108
Q

when did pangea break up

A

175 Ma, and the jurrassic.

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