Geology 12Geology 12

PresentsPresents

Hand out note helper WS 8.1

Geologic Time

A: Fossil Record & Geologic Time Scale

B: Relative Dating

C: Absolute Dating

A: Fossil RecordA: 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

• b) trails: imprints of body parts (dino hide)

• c) burrows: made by worm & shrimp in soft sediment before lithification

• d) borings: holes made in shells or solid rock

• e) coprolites: feces

Dinosaur hide

2oma Beaver burrow

Footprints of father-son 3.6 myrs ago in volcanic ash

-3. Mold/Cast

1. Shell buried

1. Shell buried

2. Shell dissolved

(void space)

2. Shell dissolved

(void space)

3. Rock split to reveal mold

mold

3. sediment/precipitate deposited in mold)

4. Rock split for reveal cast

a) Mold: cavity that preserves organism’s shape.

b) Cast: sediment fills in mold to preserve organism’s shape.

castmold

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 Y

Fossil X

• Ex B Try to do it without fossils

200 km

230 km

3000 m

elevation

2200 m

elevation

1500 m

elevation

2000 m

elevation

1200 m

elevation

500 m

elevation

• Ex B Try to do it without fossils

3000 m

elevation

2200 m

elevation

1500 m

elevation

2000 m

elevation

1200 m

elevation

500 m

elevation

Fossil A

Fossil B

Fossil C

Fossil D

Fossil D

Fossil E

Fossil F

Fossil G

Fossil H

Fossil F

Fossil H

Fossil G

Fossil I

Fossil J

• 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

• Examples see note helper WS 8.1 p.4

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Best index fossil = Age of rock is

Tim

e

Foss

il A

Foss

il B

Foss

il C Fo

ssil

D

B silurian

• Examples see note helper WS 8.1 p.4

Quanternary

Tertiary

Cretaceous

Jurassic

Triassic

Permian

Best index fossil = Age of rock is

Tim

e

Foss

il E Fo

ssil

F

Foss

il G

Foss

il H

F 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

intertidalHigh tide

Low tidesubtidal

bathyal

• 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– Common during times following large

extinctions Ex: mammals after dinosaurs

morphology

tim

e

Cretaceous extinction

• 2. Convergent Evolution: 2 organisms become more alike– Ex: succulents & cacti, dolphin & penguin

morphology

tim

e

• 2. Convergent Evolution: 2 organisms become more alike– Ex: succulents & cacti, dolphin & penguin

• 3. Divergent Evolution: 2 similar organisms become more different through time– Ex: Griz and polar bear

morphology

tim

e

• 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.– Ex: Muskox and Mammoth

tim

e

morphology

Hand out Note helper WS 8.1 Hand out Note helper WS 8.1 p.5p.5

Which organism(s) are undergoing:

1. the greatest change/morphology:

2. adaptive radiation:

3. convergent evolution:

4. divergent evolution:

5. parallel evolution:

tim

e

morphology

A

B

B

EDC

A

B & C D & E

C & D

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/diseaseUltimate 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 HWDo WS 8.2 for HW

• Do WS 8.3 in class with DVD videoDo WS 8.3 in class with DVD video

Fossil Notes Part 2Fossil Notes Part 2

• PresentsPresents

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.

• 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

Mantle

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

Yellowstone Hotspot 24 – 5 ma

Columbia Basalt Flood 37 – 24 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 HistoryDo Lab 8.1 Geologic History

• Do Lab 8.2 Fossil IDDo Lab 8.2 Fossil ID

• Do WS 8.4 Geologic HistoryDo WS 8.4 Geologic History