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104 Cards in this Set

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Law to help determine relative age of any single section, in which oldest rocks are at the bottom (deposited first) and the youngest are at the top (deposited last)

Law of Original Horizontality

Strata are deposited in horizontal layers that are parallel with each other

Law of Original Continuity

Strata are continuous over lateral distance


The connections between single rock sections can build up a composite section that shows all the rock strata in the region in their proper relative ages

Relative Dating

Getting events from different places in the correct order


'New Life' - Acme of mammals, birds, and flowering plants. Hominids appear late in this era


'Middle Life' - Age of dinosaurs. Ammonites, ichthyosaurs and pleisiosaurs in the seas


'Old Life' - Age of trilobites, brachiopods, and other archaic invertebrates in the seas. First land plants, amphibians and reptiles occur late in this era

Half-life of radioisotopes

Organic fossils <60,000 can be dated directly using Carbon-14 dating (half-life of 5730 years)

Fossils >60,000 years dated by radioactive minerals; zircon in volcanic ash has U/Pb dating (half-life of 0.7-4.5 Ga)

Absolute Dating

Getting precise absolute dates for key fossil horizons and events, radioactive dating is the best

Plate Tectonics

The major unifying theme in earth science

Alfred Wegener

Proposed continental drift in 1912

Evidence of Continental Drift

1) 'Fit" of continents, especially west Africa and east South America

2) distribution of Late Paleozoic and Early Mesozoic fossils through South America, Africa, India, Antarctica, and Australia

3) consistent ice-flow directions away from the center of Gondwana

4) continuation of mountain belts across present ocean basins

Mesosaurus and Glossopteris

Critical fossil finds proving Continental Drift; Mesosaurus is a fresh-water reptile and Glossopteris is a seed fern

Evidence of Plate Tectonics

1) Atlantic Mid-Ocean Ridge matches 'fit' of continents

2) No ocean crust older than about 200 Ma (Jurassic) anywhere on Earth - Ocean crust gets older away from mid-ocean ridge

3) Paleomagnetics uses magnetic directions recorded in rocks to determine the latitude at which the rocks were formed, determining continents are moving

Subduction Zone

Where tectonic plates meet, and one moves under the other and sinks into the mantle due to gravity (Pacific Plate subducting below western South America to form the Andes)

Continent-Continent Collision

Plates collide, forming mountain belts (collision of India into southern Asia to form the Himalayas)


Megacontinent of the southern continents (South America, Africa, India, Antarctica, and Australia) from Cambrian to Cretaceous (542-100 Ma)


Supercontinent from Carboniferous to Triassic (300-200 Ma)


Supercontinent (1200-800 Ma)


Supercontinent (ca. 2000Ma)

Formation corresponds with the Great Oxidation Event

Rift Valley

Beginning of continent breakup (East Africa rift)

Linear Sea

Spreading of continent breakup (Red Se - Gulf of Aden, as Arabia separates from Africa)

Wilson Cycle

The creation and then destruction of oceans as mega/super continents break up and disperse, and then are destroyed when continents later collide. Each cycle takes millions of years to complete

Faint Young Sun

Early Archean sun only 80-85% as bright as it is today

Greenhouse effect of CO2 explains this paradox; evidence of abundant CO2 in the atmosphere

Miller-Urey Experiment

Demonstration on how organic compounds (amino acids, nucleotides and sugars) could be formed spontaneously by simulating early Archean atmosphere conditions - reaction always works if anoxic, never works if oxygen is present

Three Steps in the Synthesis of Life

1) Formation of simple organic materials

- Miller-Urey Experiment

2) Combination of simple organic molecules into complex organic molecules (DNA, RNA, Proteins) - "proteinworld" vs "RNA-world" models

3) Initiation of Replication (Reproduction)

- Spiegelman Monster and Eigen experiments

"Proteinworld" vs. "RNA-world"

Discussion on which came first, proteins or RNA. RNA can replicate itself (like DNA) and be a catalyst in reactions (like proteins) so is the more favoured model. Suggested a self-generating, anaerobic reaction can form ribonucleotide building blocks of RNA using an inorganic sugar-nucleotide precursor + phosphate

Spiegelman Monster

Shows that self-replicating living systems can consist of little more than a short strand of RNA

QB Virus (RNA of 4500 nucleotides) + Nucleotides + Replicase = Speigelman Monster (RNA of 220 Nucleotides) in 70 generations


Same experiment as Spiegelman but did not provide living organism as a seed. However, he came up with the same results

Nucleotides + Replicase = Self-Replicating String (RNA of 120 Nucleotides)

Evolution in a Test Tube

Shows it is not difficult to induce complex nucleic acids to begin replication

Warm Little Pond

Darwin's suggestion of where life might have begun, with the pond containing ammonia, phosphoric salts, light, heat, electricity and protein compounds

Hydrothermal Vents

Modern suggestion of where life originated, due to three clues:

1) Great Bombardment

2) Different prebiotic chemical reactions require different temperatures ranging from near freezing to above boiling (2-250 degrees C)

3) Extremophiles are at the roots of the universal tree of life (lived in hot, acidic waters especially in and around hydrothermal vents)

The Great Bombardment

Impact of a 100km+ projectile on Earth would produce a crater 1500km diameter, evaporating the ocean it hit, raising atmosphere temperature to 1500K and boil of the top 100m of all oceans over next 2000-3000 years

Deep sea-vents would not be affected by these impacts unless they took a direct hit

Pilbara Craton of Western Australia (Warrawoona 3.5Ga)

Barberton in South Africa (3.4 Ga)

Contain Earth's oldest fossils of stromatolites and organic microfossils (the latter in Warrawoona were formed in submarine hot springs, supporting hydrothermal vent theory)

Age of Stromatolites

Proterozoic, very abundant in Proterozoic shallow seas

Gunflint Chert

North shore of Lake Superior (nearly 2 Ga) is the most important and famous Early Proterozoic fossil locality

Stromatolites have diverse organic microfossils less than 10μm in diameter, all of which are prokaryotes

Most microfossils resemble iron-metabolizing Bacteria (very rare in modern oceans)

Banded Iron Formation

Abundant during Great Oxidation Event when banded iron layers formed in sea water as a result of oxygen released by photosynthetic cyanobacteria, combining with the dissolved iron into insoluble iron oxides, precipitating out and forming a thin layer on the ocean floor


Cannot tolerate oxygen, most early prokaryotes were this


Uses oxygen if available, otherwise uses anaerobi


6CO2 + 6H2O <-> C6H12O6 + 6O2

Fixes carbon dioxide and liberates oxygen as a byproduct of metabolism from cyanobacteria

Iron Ocean (prior to 1.8 Ga)

Stage 1 of oxygenation of the Earth

-No free oxygen in the atmosphere or oceans prior to about 2.4 Ga, and any free oxygen liberated by photosynthesis immediately combined with reduced metals (usually iron) in seawater and atmosphere

- lead to banded iron formations, and final disappearance of banded iron formation was at 1.8 Ga

Canfield Ocean (1.8-0.6 Ga)

Stage 2 of oxygenation of the Earth

- atmosphere and ocean contained limited free oxygen

-deep oceans contain abundant H2S but no free oxygen

- brief reappearance of iron ocean at 0.7 Ga in conjunction with snowball glaciations

Modern Ocean (after 0.6 Ga)

Stage 3 of oxygenation of the Earth

- atmosphere, shallow ocean and deep ocean all oxygenated

Great Oxidation Event (2.4-1.8 Ga)

Transition between Stages 1-2 of oxygenation of the Earth

- free oxygen in atmosphere and water increased 100-fold to ~5% of present levels

1) disappearance of banded iron formation

2) appearance of red soils and river deposits

3) drawdown of CO2 resulted in the first glaciations in Earth history

4) production of ozone layer shielded Earth from UV radiation

5) permitted fully aerobic metabolism and thus eukaryotes


Metabolism depends fully on oxygen, 18X as efficient as anaerobic

Differences Eukaryotes have from Prokaryotes

1) DNA is encased in the nucleus

2) cells contain organelles - most important are mitochondria and plastids (latter used for photosynthesis)

3) complex morphology incuding spines and processes

4) ability to change shape during life (cytoskeleton)

5) ability in some to form complex multicellular units with differentiated cell types

Lynn Margulis

Suggests eukaryotes represent an endosymbiosis between a fermenter (host cell), a purple bacterium (ancestral mitochondrium) and a cyanobacteria (ancestral plastid)


Eukaryote biomarkers that may extend back to Archean (2.7 Ga) but is more probable that these may be recent contaminants

Early Eukaryotes

1) Acritarchs - large size, complex ridges/spines, appears 1600 Ma

2) Carbonaceous compressions - multicellular algae, appear at 2.1 Ga, definitely from 1.6 Ga

3) Fossil red algae - 1200 Ma, by 750 Ma also brown algae and green algae

4) testate amoebans - 750 Ma, oldest heterotrophic (predators and scavengers) eukaryotes

Grenville Mountains

Part of the Thousand Islands, records massive continental collisions that produced Rodinia

Supercontinent Cycle
Billion year cycle; studies of ice age deposits (tillites) provide a crude record over the past three billion years

- 4 major intervals of glaciation, three of which correspond to supercontinents

Greenhouse-Icehouse Cycles

Hundreds of millions of years cycle; climate fluctuation between greenhouse and icehouse conditions

-Most recent was greenhouse to icehouse was Eocene-Oligocene boundary at 38 Ma, corresponding with drift of Australia away from Antarctica and the collision of India and Asia producing Himalayas

Al Fischer

Spoke in favour of the Earth's climate alternating between ice ages and warm periods due to the Greenhouse-Icehouse concept, recognizing the climate has fluctuated at two or more scales between either condition in the Phanerozoic

Greenhouse Conditions

Warm over much of the Earth. high sea levels

Icehouse Conditions

Cold, low sea levels, ice sheets

Recognizing Greenhouse to Icehouse Mode

1) Leaf-shape analysis - smooth leaf margins with drip is tropical, serrate margins is temperate/polar

2) Oxygen isotope analysis - high 18O/16O ratios in seawater reflect large ice caps

3) Community analysis - types of fauna and flora fossils found in a specific area that are reminiscent of another area

Fossil Forest on Axel Heiberg Island

- Eocene (40-45 Ma)

- mummified forests of deciduous and conifers

- animal fossils include turtles, alligators and hippo-like creatures

- indicates warm seasonable temperature, but has 4 months in total darkness in winter

Milankovitch Cyclicity

10's to 100's of thousands of years cycles; relates to changes in the obliquity (tilting), precession (wobble) and eccentricity (ellipticity) of Earth's orbit

Snowball Earth

Series of the most severe global ice ages in Earth history, 730-580 Ma

Sturtian Glaciation (740 Ma)

First massive episode of Neoproterozoic glaciation. The first animals to evolve, sponges, postdate this event

Marinoan Glaciation (635 Ma)

Second massive episode of Neoproterozoic glaciation. Microscopic animals and embryos postdate this event

Gaskiers Glaciation (580 Ma)

Youngest Proterozoic glacial deposits worldwide. Ediacara Biota (580-540 Ma) postdate this event, and is when "Life Got Big" with the world's first large eukaryotes

Mistaken Point

UNESCO World Heritage site in eastern Newfoundland, and is where the oldest Ediacaran fossils are - 580 Ma fronds

- reflects sudden incursion of oxygen into deep oceans

- dominated by highly fractal fronds (rangeomorphs)


Highly fractal forms, representing an extinct clade, lack mouths and fed by suspension feeding or osmoptrophy


Ediacara biota form, interpreted as mobile bilaterians that grazed on microbial mats

Dawn of Animal Life

Reconstruction of Ediacara biota as primitive examples of simple crown group animals

Dolf Seilacher

Believed Ediacaran discs were benthic (bottom dwelling) not pelagic (swimming) as the Dawn of Animal Life model would imply, and created the Vendobionta to label all Ediacaran taxa more similar to each other than to modern living organisms

Garden of Ediacara

Ediacaran ecosystem almost entirely autotrophic and/or microphagous ecosystem

Stem-group Bilaterians

Root stock for Cambrian Explosion, ancestral taxa evolving into annelids, arthropods and molluscs)

Evolutionary Radiation

Most profound and rapid diversification event in history of life, happened for the Cambrian Explosion


Internal fluid-filled cavity, Cambrian Explosion mainly involved coelomates, reflecting emergence of skeletons and brains

Cambrian Skeletons

1) Crown-group radial animals, especially sponges - archaeocyathan first skeletal reef builders

2) Small Shelly Fossils- clams, molluscs, snails, sclerites

3) Brachiopods

4) Trilobites - dominant group of Cambrian

5) Echinoderms and Chordates

Cambrian Brains

Simple horizontal Ediacaran burrows turned into consistent complex patterns of Cambrian burrows

Burgess Shale

Exceptional preservation of hard and soft-bodied marine animals, most important fossil Lagerstatten of all time.


Top carnivore of Cambrian seas, up to a meter long with superb vision

Causes of Cambrian Explosion

1) Rise in Oxygen

- higher oxygenation especially favours predators, a key part of Explosion

2) Ecological Feedback (triggering factor)

- Cambrian Arms Race development of increasingly sophisticated armour and weapons

-led to Agronomic Revolution

Gene Pool

Total amount of genetic information coded on all of the individuals in the population


The continual evolution of a species until it imperceptively becomes a new species


Splitting of one species into two as different populations of the species respond to changing circumstances in different ways


Similar life habit in a similar environment leads to the evolution of similar morphology among organisms that are completely unrelated


Evolved independently at least five times: 3X placental mammals, marsupial mammals, and therapsid reptiles


Organisms evolve as a response to changes in their environment, but also in response to evolutionary changes in other organisms

"Arms Race"

-carnivore vs. prey animals (carnivore increase speed, power or complex hunting strategies, prey increase speed, camouflage, armour or poisons)

-herbivore vs. plants (adaptations of plants may include spines or poisons)


Relationship between two species that is beneficial to both (bees and flowering plants)

Red Queen Effect

Any evolutionary advance by one species forces the rapid evolution of all species that are dependent on it. All species must constantly evolve or they will go extinct

Court Jester Effect

Abiotic factors, which are not under the organisms control, also shape their evolution


Evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characteristics

Linnean Classification

Three Domains/Superkingdoms: Bacteria, Archaea, Eukarya

Four Kingdoms: Protoctista, Fungi, Plantae, Animalia

Phylum/Division, Class, Order, Family, Genus, Species


Organisms are categorized based on shared derived characteristics that can be traced to a group's most recent common ancestor and are not present in more distant ancestors


Group withe common ancestor and all of its descendents


Clade excludes more than one ancestor (corals evolved separately from different anemone groups)


Has a common ancestor but does not include all descendants (reptiles have a single common ancestor but do not include mammals or birds which are also their descendants

Three Sets of Morphological Characters

-Primitive (relating to original ancestral features, pleisiomorphies)

-Derived (first appear in clade, apomorphies)

- Convergent/analogous


Shows order of evolutionary appearance of derived characters

Strengths of Cladistics

-rigorous and testable

-can be used at almost any level of taxonomy

-can include fossil and living species in the same cladogram

-shows sibling relationships (not ancestor-descendant)

Molecular Phylogeny

Directly measures degree of substitution in DNA, RNA or proteins to see genetic differences

Strengths of Molecular Phylogeny

-rigorous and testable

-can be used at any level of taxonomy

-directly measures genetic differences

However, with exception to amber, can only be used on modern organisms

Category of Fossils: Bones

-made of phosphate

-taphonomy (conditions of fossilization) critical to determining how and if bones are are preserved

Category of Fossils: Shells

-made of carbonate, or less commonly silica or phosphate

- concentrated by waves or currents and can leave molds in the rock

Category of Fossils: Cellulose

- preserved if plant is mummified or if oxygen is excluded and plants are not deeply buried

- wood can become petrified if pores are filled with silica (quartz)

- cellulose buried more than a few 100m deep will become carbonized by heat and pressure

Category of Fossils: Trace Fossils

-tracks, trails, burrows, and borings of animals

-record the ethology (behaviour) of the animal that made them

Category of Fossils: Soft Tissue

- deposits are fossil Lagerstatten