GLG Exam 1

catastrophism theorizes earth was shaped by catastrophes (i.e. Noah’s flood); young earth

• idea that natural laws of the past were not the same as the current natural laws

uniformitarianism theorizes earth was formed through slow processes (i.e. erosion)

• idea that the same patterns and processes of the past are occurring today; ancient earth

Named after Neptune, Roman God of the Sea because believers theorized that each type of rock came from a specific time, and that they originated in the primeval ocean

• primary rocks (granite)→ precipitation

• transitional rocks (nonfossiliferous sed)

• tertiary rocks (alluvial poorly consolidated sed) seen as modern rock

• volcanic (minor importance) → crystallized from water

Hutton’s Uniformitarianism

• continuous upcycle of uplift, erosion, deposition, burial, re-uplift

• same processes ; unchanging laws

• ancient earth + deep time

Lyell’s Ultra-Uniformitarianism

• same laws AND rates

• all geologic processes are gradual (no catastrophe)

• no process witnessed by humans had geologic importance

• all rocks and organisms were unchanging

• extinct organisms would reappear

Actualism is a reformed version of uniformitarianism by allowing space for catastrophic events

• natural laws are constant but processes vary

• earth’s systems have evolved over history and continue to do so

(ALL for PT)

Wegener: proposed theory of continental drift

du Toit: established fossil evidence

Hess: sub-marine surveys figured mechanism was from convection cells at Mid Ocean Ridges

• Hess proposed Seafloor Spreading

Vine & Matthews: seafloor paleomagnetic data as evidence for SFS -- magnetic polarity reversals matched ocean floor basalts at Juan de Fuca Ridge

Wilson: put together final touches (Earth’s surface has lithospheric plates (C or O) divergent and transform boundaries, O lithosphere recycled into mantle at subduction zones)

• Marie Tharp: used sound waves to create ocean map that backed up continental drift by showing V shape running along mid-atlantic ridge

• “fit” of continents

• location of glacial deposits

• similarities of rock types and structures (folds, faults)

• paleoclimate evidence

• distributions of certain fossils

Wegener didn’t have a mechanism to explain why the tectonic plates moved

• Guyots: isolated underwater peaks with flat tops

• Depths of guyots (and sea floor) increased along linear trends

• only 1/16th of expected sediment and volcanic islands

Hess saw long chains of underwater mountains with rift valleys in the center , now called Mid-Ocean Ridges

‘60s Deep Sea Drilling Program dated seafloor rocks + sediments, confirming sea floor age data and validating both sea floor spreading and plate tectonics

young ocean basin rock is generated when hot convections cells cause ocean basin rock at MOR to move away from ridges. rock cools and settles as it moves away from the heat to form guyots. old ocean crust sinks back into mantle at deep-sea trenches.

water is crucial because:

• it lubricates subducting slabs

• flux melting

• descending slabs become denser when they lose water

we care about Pangaea because putting the continents together makes glacial deposits, rock types, paleoclimate and paleontological evidence, and paleomagnetic evidence to all line up for continental drift.

Steno:

• superposition: in any succession of sedimentary rock layers lying in their original horizontal position, the rocks at the bottom of the sequence are older than those lying above

• lateral continuity: sediments are deposited in layers that extend laterally in all directions until either reaching the edge of basin or thin out and terminate

• original horizontality : sediments are deposited in layers that are horizontal or nearly so

Hutton:

• inclusions: any inclusion in a rock is older than the rock containing it

• cross-cutting relationships: faults, fractures, igneous intrusions, and erosional surfaces that cut across a given stratum or series of strata are younger than the rocks containing it

• recognized and understood unconformities

Relative dating - based on rock layer + other found items

Numerical dating - uses number of half-lives experienced by a rock

Can be used together to see order of events in age order as well as actual age

isotopes are elements with a different amount of neutrons

Radioactive isotopes with slow decay rate can be used to find the half-life and age of rocks in their chemically closed system.

British geologist who came up with the first reliable radiometric ages for rocks.

Author of The Age of the Earth

Estimated age of earth as 4.5 billion years old

To calculate numerical ages, there must be parent isotope material in original rock with no decay having begun.

There must be no loss or gain of P or D except through radioactive decay (closed)

Half-life must be appropriate to event

(ASK)

There is inherent error within every growing daughter / decaying parent so using multiple systems to double check is useful for accuracy

Lithification transforms loose sediment particles into solid rock

• compaction: Pressure from overlying material places grains closer to each other

• Cementation: Precipitation of quartz, calcite, or iron oxide around grain perimeters (binds grain together)

Siliciclastic (clastic) rocks are formed from weathered bits of pre-existing rocks

Textural:

Grain size:

Conglomerate or breccia, sandstone, siltstone, claystone, mudstone

Sorting: Well to poorly sorted

Degree of rounding reflects transport distance (farther= rounder)

Grading: Due to current strength variations (e.g. Coarsening upward)

Composition:

• Dominance of quartz implies longer transport from source area

• Dominance of feldspars and/or rock fragments implies shorter transport from source area

• Quartz, feldspar, rock fragments, percent Matrox (finer grains)

The larger, generally 3-D physical features of sedimentary rocks; best found in large outcrop instead of through microscope

Lamination, beds, cross-bedding, graded bedding, trace fossils, mud cracks, ripple marks

Limestone: Minerology dominated by calcite or aragonite

Dolostone: Minerology dominated by dolomite

Formed from the shells and bodies of underwater organisms

this means rocks units are not time units. Sedimentary rock layers differ in age from place to place.

correlation: establishing the relationships between the order of events in two or more locations

• lithostratigraphic correlation matches rock units w/o regard for time

• time-stratigraphic correlation uses fossils to demonstrate time-equivalence of rock units

unconformities represent gaps in the rock record.

lithostratigraphy involves the classification of any rock where biostratigraphy deals only with fossiliferous rocks

William Smith

Principle states that the biological history on earth is captured within rocks based on their fossils. All rocks with the same types of fossils were deposited during the duration of that species existence on Earth.

The Principle of Faunal Succession in application created Biostratigraphy

• only practical dating method for geologic history as well as correlating strata in search of oil and gas

• easy to recognize

• short stratigraphic range: precise dating

• large geographic range: abundance

• found in many environments: abundance

• easily preserved

Types of Zones:

1. taxon range zone

2. concurrent range zone (2 or more taxa)

3. lineage zona: based on successive first occurrences within a single evolving lineage

4. interval zone: 2 successive first or last occurrences of unrelated taxa

5. abundance zone: sudden increase n number of certain taxon

Determined by evolution and paleoecology

Facies Fossils are appear and disappear; controlled by changes in sedimentary faces.

• many biostratigraphy zonation’s fail b/c key taxa were facies controlled

First Appearance Datum (FADs): abundance

Last Appearance Datum (LADs): extinction

Lazarus taxa: facies fossils

Elvis taxa: extinction confusion when taxa look alike

Zombie taxa: when durable fossils are eroded and redeposited, giving impression that taxa survived longer than they did

Concurrent range zone is the most robust because there are 2 or more taxa’s range zones overlapping.

magnetic: dating based on magnetic reversals

chemo: dating based on isotopic ratios

cyclo: how astronomically forced cycles affect dating

event: dating of strata, fossil assemblage intervals, and interfaces

• marker beds (like ash between sediments) show distinctly that an event occurred within strata

the GSSP defines the base of each stratigraphic unit by name and rank.

These reference points of stratigraphic sections of rock define the lower boundaries of stages on the International Chronostratigraphic Chart.

body fossils require hard parts: carbonates, silica, calcium phosphates, complex organics (cellulose, chitin, spongin)

• unaltered remains (amber), permineralization, recrystallization, dissolution & replacement, carbonization, compressions/impressions

trace fossils (ichnofossils) are biologically generated sedimentary structures

• tracks, burrows, fecal pellets, etc

(rapid burial, anoxic burial environment)

organism makeup:

• hard (inorganic) vs soft (organic) parts

• number of skeletal elements

• mineral composition of hard parts

ecology:

• numerical abundance

• size of organism

• habitat

  • terrestrial: subjected to net erosion

  • subaqueous: subjected to net deposition

    • infaunal (living in sediment) OR epifaunal (living on or above sediment)

taphonomy: study of death, decay, burial, fossilization (‘grave’ → found)

• biostratinomy: processes occurring between death and final burial (stratification laws- biological & mechanical agents, chemical degradation)

• diagenesis: processes occurring after final burial (compaction, dissolution, replacement)

mechanical: transport, breakage, exhumation

chemical: oxidation & early changes in minerology

biological: decay, scavenging, bioturbation, encrustation, boring

bioturbation: the disturbance of sedimentary deposits by living organisms

• performed by infaunal organisms (live/burrow into sediment)

• causes disarticulation

“storage place” in English

significance: extraordinary fossil deposit that preserves soft tissues and sometimes even skin texture and color patterns

depositional conditions: rapid burial + anoxic burial environment

evolution: descent with modification

all life has common ancestor

natural selection: variability in traits → traits enhancing survivability → heredity of desirable traits

Jean Baptiste de Lamarck: ‘inheritance of acquired characteristics’ traits arise from need and are heritable

Charles Darwin: species change, natural and artificial selection

Alfred Russell Wallace: same conclusions as Darwin; encouraged publication of ‘On the Origin of Species’

Gregor Mendel: pea plant experiments;

• traits controlled by genes which occur in multiple forms (alleles). alleles may be dominate or recessive and the offspring received one allele from each parent

• particulate inheritance→ F2 experience 1/4 recessive expression

Mutations (failed DNA copy OR external influences)

Migration (gene mixing)

Sex recombination (new gene combinations)

Genetic drift (lucky/unlucky gene survival)

Natural selection (desirable traits survive)

allopatric speciation: new species from mixed homelands

• phyletic gradualism: continuous and gradual minor change over time

• punctuated equilibrium: long periods of no change interrupted by rapid change (bottleneck effect)

divergent evolution: different environmental pressures bring about accumulated differences in closely related population within species → speciation

convergent evolution: independent evolution of similar features in species of different lineages (bat wing / bird wing / insect wing)

microevolution: gene frequency changes in population over a generation

macroevolution: major feature changes in species; wings, legs, etc)

homeotic genes are regulatory genes (“master switch”) which cause replacement of organ systems in organisms

• the DNA code itself is a homology that links all life on Earth to a common ancestor

homology: similar characteristics due to relatedness

the fossil record: biostratigraphy showing evolution of common ancestor over time

cellular & molecular evidence: likeness in cell structure & DNA

vestigial features: anatomical remnants of ancestors

transitional fossils (transitional forms) show intermediate states between ancestral form and that of its descendants

developmental biology: study of embryological development; comparative embryology reveals fundamental development similarities

ecology: environment affects the evolution of living things

3 domains: Bacteria, Archaea, Eukarya

Archaea and Eukarya are more closely related

LUCA: Last Universal Common Ancestor; microbe

(biologists) Biological species concept: a group of populations that are actually or potentially inter-breeding and are reproductively isolated from other such groups under natural conditions

(paleontologists) Morphological species concept: Organisms classified in the same species if they appear ‘identical’ by morphological (shape) criteria

• original difficulty for paleontologists to use the biological species concept because, for fossils, naturally occurring interbreeding populations cannot be tested

Phylogeny: Evolutionary history of a genetically related group of organisms

Difficulties in reconstructing tree of life:

1. Don't know the total diversity of living organisms

2. Know even less of the diversity of fossil organisms

3. How to tell if fossil is direct ancestor to another fossil and not a close relative of that direct ancestor?

Cladistics is a taxonomical technique developed as an approach to making phylogenic trees

• needs both phylogenetically informative characters and uninformative (misleading) characters to avoiding using them

Homologies (homologous traits) * useful

• Similar traits due to common ancestry

• Traits evolve and can be modified

• useful for recognizing / defining closely related groups of organisms

• Hair, skeletal elements, feathers

Homoplasies (convergent traits) *not useful

• analogous traits evolved independently in separate lineages due to similar ecological pressures

• False similarity, not due to common ancestor

• Wings, eyes, flippers

molecular phylogeny is an approach to making phylogenic trees using DNA, RNA, etc.

the analysis of molecular similarities and differences between proteins, amino acids, antigens, chromosomes + DNA to evaluate their evolutionary relationships.

More robust than anatomical phylogeny because there are less homoplasies and the data is readily quantifiable