Download Geology 12 - First Class

Geology 12
Presents
Hand out note helper WS 8.1
Geologic Time
A: Fossil Record & Geologic
Time Scale
B: Relative Dating
C: Absolute Dating
A: Fossil Record
A: Fossil Record & Geologic Time
Scale
• Paleontology: study of fossils
• Taphonomy: preservation of organisms
• For fossilization to occur, it requires:
– 1. organisms must possess hard parts
(shell, bones, teeth)
– 2. favourable environmental conditions –
rapid burial to prevent physical and
biological destruction (soft seds’ for
delicate organisms)
– 3. large population helps
Hard Parts
Rapid Burial
Large Population
• Types of Fossilization
(remember WS 6.2)
– 1. Body Fossil
• a) unaltered
– i) soft parts
(woolly
mammoth)
– Preserved in
permafrost,
amber, tar pits
– ii) hard parts
(bones, teeth,
shell)
• b) altered
–i) permineralization: material is
added to pore spaces (silica)
…silicified wood.
–ii) replacement: original material is
dissolved and replaced by another
material molecule by molecule.
–iii) recrystalization: mineral
recrystalizes into another (shell:
aragonite -> calcite)
–iv) carbonization: volatiles escape
leaving only carbon (plant/leaf)
– 2. Trace Fossils
• a) track: foot prints
2oma Beaver
• b) trails: imprints of bodyburrow
parts
(dino hide)
• c) burrows: made by worm &
shrimp in soft sediment before
lithification
• d) borings: holes made in shells
hide
or solidDinosaur
rock
• e) coprolites: feces
Footprints of
father-son 3.6
myrs ago in
volcanic ash
-3. Mold/Cast
a) Mold: cavity that preserves organism’s
3. Rock split to
shape.
1. Shell
buried
2. Shell
dissolved
(void space)
reveal mold
b) Cast: sediment fills in mold to
preserve organism’s shape.
3.
2. Shell
1. Shell
dissolved sediment/precipitate
buried (void space) deposited in mold)
mold
4. Rock
split for
reveal
cast
cast
mold
Mold of Trilobite
• The Fossil Record:
– Incomplete: not all organisms preserved
– Biased towards:
• 1. organisms with hard parts
• 2. organisms that lived in shallow marine
environments (best chance of rapid burial
• 3. organisms with large populations
Uses of Fossils
• 1. Correlation (lateral continuity)
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Uses of Fossils
• 1. Ex A (see note helper WS 8.1 p.3)
Fossil X
Fossil X
Fossil Y
Fossil Y
Fossil X
Fossil Y
• Ex B Try to do it without fossils
3000 m
2200 m
1500 m
elevation
elevation
elevation
200 km
230 km
2000 m
1200 m
500 m
elevation
elevation
elevation
• Ex B Try to do it without fossils
3000 m
Fossil A
elevatio Fossil D
n
Fossil E
Fossil B
Fossil D
elevatio
n
Fossil G
2000 m
elevatio
Fossil H
Fossil F
Fossil G
elevatio
n
Fossil H
Fossil F
Fossil C
1500 m
2200 m
Fossil I
1200 m
elevatio
n
500 m
Fossil J
elevation
• 2. Paleoenvironments: shallow or deep
marine
• 2. Paleoenvironments:
land, shallow or deep
marine
• 3. Paleoecology: how organism adapted,
related to other organisms.
• 3.
Paleoecology:
how organism
adapted,
related to other
organisms.
• 4. Paleogeography: tells distribution of
land,seas, paleolatitude, shorelines and
land connections. Ex: fern leaf = land/swamp
• 5. Paleoclimates: hot, cold, wet, dry
– Ex: palms in hot climate.
• 6. Evidence
of Evolution:
change over
time in
species.
• 6. Evidence of Evolution: change
over time in species.
• 7. Evidence of Plate Tectonics
• 7. Evidence of Plate Tectonics
• 8. Index Fossils: determine the age of
bedrock unit if you time when fossil lived.
• What makes a good index fossil:
– a) existed for a relatively short period of time
– b) widely distributed around the World
– c) easily identified
– d) readily preserved
Most important
Fossil D
Fossil C
Fossil B
Fossil A
Time
• Examples see note helper WS 8.1 p.4
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Best index fossil = B Age of rock is silurian
Fossil H
Fossil G
Fossil F
Fossil E
Time
• Examples see note helper WS 8.1 p.4
Quanternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Best index fossil = F Age of rock is cretaceous
Marine Environments
• 1. Benthic = bottom
– a) supratidal = above high tide (aver’ sea-level)
• (covered only during floods or storms)
• One of the toughest environments to exist
• Is beach area
– b) intertidal = between high and low tides
• brackish during rain/super saline during the
sun
• Another tough place to exist
– c) subtidal/sublitoral = low tide to edge
of continental shelf
• Most life (coral reefs)
– d) bathyal = on continental slope
• 200 m to 4000m deep
– e) abyssal = ocean bottom
• 4000 m
– f) hadal = down the trench
• Down, down, … 11,000 m
supratidal
High tide
intertidal
subtidal
Low tide
• 2. Pelagic = in water column (swim/float)
– a) Neritic = above continental shelf
– b) Oceanic = above deep ocean basins
Life Habits
• 1. Planktonic = organisms that float
within the water column
– Ex. Jelly fish, plankton
• 2. Nectonic = animals that swim within
the water column
– Ex. Fish, dolphins, whales ,
ammonites
• 3. Benthonic = live on bottom
– a) infauna – live within the sediment
• Ex: worms
– b) epifaunal – live on the sediment
• i) vagile = vagrant = move about
–Ex: lobster, starfish
• ii) sessile = stationary
–Ex: coral, barnacle, sponge
Evolution
• Evolution Theory = change over time
through natural selection (through
variation via mutations, within a species
and the struggle to survive, only the
“fittest” offspring live to reproduce and
pass on their genes.
• How fast?
– Darwin believed in Phyletic Gradulism
(PG): slow, gradual evolution over many
generations
VS.
Punctuated Equilibrium (PE) occurs rapidly
over short periods of time followed by long
periods of little or no change.
PE: Caused by organisms living at the edge of
environment under the greatest evolutionary
pressure. These organisms undergo the
greatest change, and if:
i) the environment changes for the worst
these organisms will be better prepared for
survival than the main body.
ii) the organism is re-introduced to the main
environment, their superiority could result in
extinction of the mother species.
Evidence for Evolution
• 1. Anatomical:
– a) Embryology: close resemblance of
embryos under development
– b) Homology: (homologous structures): bones
of limbs have been modified for different
functions through evolution.
– c) Vestigial Structures: inherited organs that
now serve no purpose
• 2. Biological
– a) Selective Breeding: man has caused
microevolution over the last 10,000 years by
breeding plants and animals for certain
characteristics
• Ex: dog, wheat
– b) Ontogenetic changes: evolutionary
changes that occur during an organisms life
time:
• Ex: egg -> catepillar -> pupae -> butterfly
• Ex: egg -> tadpole -> frog
– c) Biochemistry: similarity between
organisms implies common ancestry
• Ex amino acids
Common
amino acids
• 3. Paleontological: ample evidence in the
fossil record demonstrates evolution
Ex: Homo habilus -> Homo erectus -> Homo sapien
Patterns of Evolution (4)
• Orthogenesis = change in morphology
(body structure) over time.
• 1. Adaptive Radiation: a species evolves
quickly over a short span of time into
different species
time
– Common during times following large
extinctions Ex: mammals after dinosaurs
morphology
Cretaceous
extinction
• 2. Convergent Evolution: 2 organisms
become more alike
time
– Ex: succulents & cacti, dolphin & penguin
morphology
• 2. Convergent Evolution: 2 organisms
become more alike
– Ex: succulents & cacti, dolphin & penguin
• 3. Divergent Evolution: 2 similar
organisms become more different
through time
time
– Ex: Griz and polar bear
morphology
• 3. Divergent Evolution: 2 similar
organisms become more different
through time
– Ex: Griz and polar bear
• 4. Parallel Evolution: 2 organisms
change in the same way.
time
– Ex: Muskox and Mammoth
morphology
Hand out Note helper WS 8.1 p.5
time
A
B
C
D
morphology
Which organism(s) are undergoing:
1. the greatest change/morphology: B
2. adaptive radiation: A
3. convergent evolution: B & C
4. divergent evolution: D & E
5. parallel evolution: C & D
E
Causes of Extinction
• 1. Plate Tectonics
– a) fast modification of climate
• Ex: Megladon (giant shark) vs. American
land bridge
– b) plates come together introducing
non-indigenous species
1 continent
1 continent
• 2. magnetic pole reversal and cosmic
rays
– No magnetic field = more cosmic rays
• 3. meteorite/asteroid impact
– Permian 245 ma 80% of species extinct
– Cretaceous 66 ma 50% species extinct
• 4. new predator/parasite/disease
Ultimate
Predator: Mother
Inlaw
• 5. volcanism: ash blocks sunlight
• 6. supernova nearby radiates life
– Ordovician extinction of all life within
10 m of surface
– Pos’ cause for Mammoths demise
• Do WS 8.2 for HW
• Do WS 8.3 in class with DVD video
Fossil Notes Part 2
• Presents
Geologic Time Scale
• A: Earth: the beginning
• 1. 4.5 ba = 4,500 ma = Earth forms from
molten ball of magma heated by
meteorite impact collisions.
• 2. Earth: inner-solid
outer-molten (no solid crust)
– Atmosphere = H2, methane, ammonia,
H2S, N2, Ar, water vapour.
• 3. Rapid convection currents and magma
differentiation occurred (remember Chps
3-4)
– a) fractional crystalization (Fe-Mg mins’ )
– b) more silisic rocks have lower melting
temperatures -> melted 1st -> rose to surface
Molten iron
sinking
towards core
• 4. Convection current drove lighter/more silisic
material together (form early continents) while
heavier/more mafic material subducts.
Mantle
• As these small pieces of silisic rock were driven
against each other, they formed early continents
by continental accretion, later to become
cratons.
– Largely igneous and gneissic rocks
– 4.0 ba oldest still in existence in Greenland
Continents collide becoming ever larger as they
accrete silisic crust that has formed on the surface
of the Earth.
• 5. Outgassing of volatiles (mainly
water) from molten rock began 4.5
ba and was fairly complete (oceans
filled) by 2.0 ba.
• B: Life
• 1. 3.7 ba = first life appeared:
stromatolites, an algae structure
(procaryotic = no nucleus)
– Single celled organisms that dominated 3.7
ba to 570 ma
– Lived in shallow marine (intertidal - subtidal)
– Used fermentation initially for energy (like
black smokers)
stromatolites
• 2. 3.0 ba photosynthesis begins with
cyanobacteria (other bacterias also form)
– Atmosphere converted from CO2 to O2
• 3. 2.5 to 2.0 ba: red beds of iron oxide
form as iron oxidizes from free oxygen
2.3 ba: first glaciation period
• 4. 2.0 eucaryotes (have nucleus)
form
– First carbonates (Lst & dolomite)
• 5. 2nd glacial period (Ice Planet)
Ice is 10 m at equator in ocean!
• C: Explosion of Life (570 ma to recent)
• Ice age ended and new seas opened up
allowing new organisms to spread out and
open new niches
– (more on evolution in Lab 8.1 and Lab 8.2)
“Explosion of Life”
• D: Geology of West Coast
• Orogeny = mountain building
– 320 – 245 ma (Penn’ –Permian): Appalachian
Orogeny in eastern US
– 208 – 66 ma (Jurrasic – Cretaceous): BC
Terranes (islands like Japan, New Zealand)
accrete onto Alberta.
– 70 - 45 ma (Cretaceous – Eocene) Laramide
Orogeny (Rocky Mtns’)
Appalachian
Orogeny
320-245 ma
– 144 – 37 ma (Cret’ – Eocene): major
magmatism in BC (Hydrothermal ores!)
– 37 – 24 ma (Oligocene) : Columbia Plateau
(Builds up 2500m thick!)
– 24 – 5 ma (Miocene): volcanism: Yellowstone
Park begins
– 6 ma (Pliocene) Grand Canyon starts to cut
– 2 ma to recent (Pleistocene) Cascade/Skagit
Mtns’ and Cascade Range (volcanoes) forms
– 1.4 ma (Pleistocene): period of continental
glaciation (3rd in Earth’s history) (4 N Am. Ice
periods)
Coast Range of BC (+ Sierra Nevada)
144 – 37 ma
Columbia Basalt Flood 37 – 24 ma
Yellowstone Hotspot 24 – 5 ma
Grand Canyon began 6 ma
Skagit Mountains 2 ma to recent
4th Ice Advance
during last 1.4 ma
(Pleistocene
Glaciation)
Geologic History
• = subdivisions of the Earth’s history by:
• 1. appearance and disappearance of particular
fossils (index)
– Ex: Phanerozoic= time that all life has existed
–
Paleozoic = ancient life 570 – 245 ma
–
Mesozoic = intermediate life 245 – 66 ma
– Age of reptiles & conifers
–
Cenozoic = recent life 66 ma to now
– Age of mammals & flowers
• 2. Location of certain rock
sections
– Ex: Cambrian = Wales
– Ex: Jurassic = Jura Mtns’ in France
– Ex: Devonian = Devonshire in
England
• 3. Type of Rock
– Ex: Cretaceous = creta = chalk
– Ex: Carboniferous = coal
• Do Lab 8.1 Geologic History
• Do Lab 8.2 Fossil ID
• Do WS 8.4 Geologic History