CO6 GEO

James Hutton

James Hutton

father of geology

bald

Uniformitarianism

the present is the key to the past

This principle developed in the early 1800’s

led Earth scientist to realize the Earth was very old – at least

millions of years old

actualism

more modern term of uniformitarianism

numerical age

actual age given in years or other unit of time

relative time

the sequence in which events took place

Contacts

surfaces separating successive rock layers (beds)

Formations

bodies of rock of considerable thickness with

recognizable characteristics allowing them to be

distinguished from adjacent rock layers

relative age

order of events or objects, from oldest to youngest

Original horizontality

beds of sediment deposited in water are initially formed as

horizontal or nearly horizontal layers

Superposition

within an undisturbed sequence of sedimentary or volcanic rocks, layers get younger from bottom to top

lateral continuity

original horizontal layer extends laterally until it tapers or

thins at its edges

cross cutting relationships

a disrupted pattern is older than the cause of the disruption

• Intrusions and faults are younger than the rocks they cut through

Baked contacts

contacts between igneous intrusions and surrounding rocks, where surrounding rocks have experienced contact metamorphism

inclusions

fragments embessed in host rock are older than the host rock (»????)_

uncomfortmities

surface (contact) that represents a gap in the geological record

discomformities

the unconformity contact separates beds that are parallel

Angular unconformities

the unconformity contact seperates a younger layer above from a lower layer that is tilted

Nonconformity

an unconformity

in which an erosional surface on

plutonic or metamorphic rock has

been covered by younger

sedimentary or volcanic rock

Correlation

The determination of

the time – equivalency of rock units

Physical continuity

physically

tracing a continuous exposure of a

rock

isotopic dating

puts absolute values

(for example, millions of years) on the

ages of rocks and geologic time periods

Isotopes

varieties of the same element

that have different numbers of neutrons

in the nucleus

Radioactive decay

the spontaneous

nuclear change of isotopes with

unstable nuclei.

• Alpha emission, Beta emission and

Electron capture

Half-life

time it takes for a given

amount of radioactive isotope to be

reduced by half.

Precambrian

represents 87 % of geologic time and is divided into

three Eons (Hadean, Archean, Proterozoic)

Phanerozoic EON

most recent eon that includes all geologic time with

abundant fossil record

• composed of

  • Paleozoic

  • Mesozoic

  • • Cenozoic

James Ussher

“Earth created in 4004 B.C. based on the Bible”

4.56 billion years

Today numerical dating gives age for Earth of _____

• Earth and the rest of the solar system was very likely formed at this time

Marine and transitional environments

are more favorable for fossil preservation than are continental environment, because the rate of sediment deposition tends to be higher

Index fossils

aka guide fossils or indicator fossils

• basis for defining boundaries in the geological time scale and the time correlation of strata

Absolute Dating

It provides a method for measuring geologic time

directly in terms of a specific number of years

Alpha particles

may be emitted from

the nucleus. ___________ consists of

two protons and two neutrons. After

emission, the mass number of isotope is

reduced by four and the atomic number is

decreased by two.

beta particle

When _______ or electron is

given off from a nucleus, the mass

number remains unchanged because

electrons have practically no mass. The

atomic number increases by one because

the nucleus contains one more proton

than before

Eon, Era, Period, Epoch, Age

geological time scale from longest to shortest

Precambrian

• Hadean

• Archean

• Proterozoic

_ 87% of earth’s history

• named after hades

  • • The Earth undergone differentiation

    • The Moon formed (perhaps based on the Impact Theory)

    • The surface was an ocean of magma until 4.4 Ga based on zircon

    • Outgassing occurred forming the first ocean

Archean Eon

“Beginning”

- Starts at around 3.85 Ga where there is a substantial

amount of crustal rocks.

The advent of the _____ marked the time when the

crust was locally cool and stable for rocks to survive

• plate tectonics occured at this time

by the end of this eon, 80% of the earth’s continental land had formed

Stromatolites

developed at around 3.2 Ga due to

cyanobacteria secreting a mucus-like substance to

which sediment settling from water sinks.

Stanley Miller

an exobiologist,

achieved the laboratory

synthesis of amino acids.

• He simulated the early

atmosphere in a laboratory

flask and then sent sparks of

electricity into the mixture.

• The liquid yielded amino acids

and other complex

compounds.

PROTEROZOIC EON

• Spans from 2.5 Ga to 542 Ma

• Encompasses almost half of the Earth’s history

• The surface environment changed from fast-moving

plates, small continents, and an oxygen-poor

atmosphere to an environment similar to today’s world

• The continents formed by at slower rates

• The interior of continents started to cool and strengthen

thus becoming relatively stable

Rodinia

first supercontinent on Earth, formed during 1 Ga

Grenville Orogeny

Rodinia’s formation triggered a mountain building

event known as the _____

Pannotia

Rodinia broke away and formed a short-lived supercontinent called ______

Proterozoic

At the beginning, life on earth was ______

BANDED IRON

FORMATIONS

Alternating

layers of quartz

and iron rich

layers

CRYOGENIAN GLACIATION

Near the end of the Proterozoic, 90% of entire Earth was

covered in ice in an event known as the _________ OR SNOWBALL EARTH

The Great Ordovician Biodiversification Event

occurred 40 million years after the Cambrian Explosion

• New species, genus, family, and order different

taxonomic levels diversified.

• The first crinoids and first vertebrate animals (the

jawless fish) appeared during this time.

Antler Orogeny

the west of the US collided with an island arc

thus causing the ________—

SILURIAN PERIOD

Early land plants appeared during this time.

• The first jawed fish evolved known as the Acanthodians

devonian period

• Age of the Fish

• First Amphibians

• First Insects

• Mass extinction near the end of this period

CARBONIFEROUS PERIOD

First appearance of gymnosperms

• Proliferation of coal-forming swamps

• Diversification of amphibians

• Appearance of reptiles

Permo-Triassic Extinction

The largest mass extinction in the Earth’s history.

• happened in permian period

• 95% of marine species died

• One hypothesis is due to massive volcanism in now

Siberia where volcanic flood basalts formed known as

“Siberian Traps”

• PANGEA WAS FORMED

ORNITHISCIANS

• Bird-hipped dinosaurs

• BIRDS DID NOT EVOLVE FROM THEM

SAURISCHIAN

• Lizard-hipped

dinosaurs

CAMBRIAN EXPLOSION

A remarkable diversification of life occurred during this

time.

• The reason for the abrupt diversification of life during

this time is unknown for certain.

• However, it is known that the evolution of hard parts

such as shells occurred this time as well the rise of new

phyla

ORDOVICIAN MASS EXTINCTION

Due to a brief glaciation and associated sea-level

lowering, a mass extinction occurred at the end of the

Ordovician period.

Triassic period

appearance of the first mammals

Jurassic Period

• during this period, ammonites began to be very abundant

• aka the age of the ammonites

• appearance of the first feathered birds

• start of the great diversification of dinosaurs

Cretaceous Period

peak of the dinosaur evolution

KT boundary

boundary between crataceous and paleogene (pg)

Mesozoic Mass extinction

dinosaurs vanished along with 90% of plankton species and up to 75% of plant species

The cause is likely due to the aftermath of a meteorite

impact as evidenced by high concentrations of Iridium

(normally found in meteorites)

Chicxulub crater

A 16-km-deep meteorite crater is found in Mexico

known as _______

CENOZOIC ERA

Subdivided into several epochs

Three periods

• Paleogene

• Neogene

• Quaternary

The appearance of Earth gradually

produced what we could see

today

• Formation of the largest orogenic

  belt due to the closure of the

  Tethys Sea forming the AlpineHimalayan Chain.

• The predominance of mammals wherein they would

  dominate.

  Dominance of angiosperms

  First appearance of:

  • Horses (Eocene Epoch)

  • Primates and Monkeys (Eocene Epoch)

  • Whales (Eocene Epoch

PLEISTOCENE

ICE AGE

• 1/3 of the Earth’s

surface was covered in

ice

• Sculpted many

glaciated terranes

• Cause could have

been due cycles in the

Earth’s movements

MILANKOVTICH

CYCLES

• changes in the earth’s precession, orbital eccentricity, and axial tilt

Precession

• Way the Earth’s axis

of rotation wobbles

Orbital Eccentricity

The orbital path

Weather

describes what the atmosphere is doing over

short timescales

Climate

– the average weather pattern in a region over long

periods of time

Anthropogenic Climate Change

climate change related to

human activities

Thermosphere

also called the

ionosphere

Albedo

percentage of radiation reflected from the surface

Blackbody radiation

the intensity and wavelength of emitted

electromagnetic radiation depends on temperature

Greenhouse gases

include water vapor, carbon dioxide, methane,

nitrous oxide, and other

Milankovitch Theory

Changes in Earth’s orbital patterns

determine input and distribution of solar radiation over long

time scales

41,00

the tilt of Earth’s axis varies on a ______ year

timescale

Sunspots

are dark areas on the Sun’s surface that are hotter than

average

30

Approximately __% of the Sun’s

radiation is reflected back into

space

Climate feedback

conversion

of high albedo snow and ice to

lower albedo surfaces

true

Snow and Ice have high

albedo (true/false)

true

Darker surfaces have lower

albedos (true/false)

Atmospheric lifetime

each

greenhouse gas survives in the

atmosphere for different amounts of

time

Global Warming Potential

a relative

measure of each gases ability to trap

heat in the atmosphere

Aerosols

small particles suspended in the

atmosphere.

Volcanoes

releases particles and gases into the

atmosphere

Plate tectonics

alters surface albedo and ocean

circulation over million-year timescales

Paleoclimatology

the study of ancient climates

Borehole thermometry

measuring

temperatures deep in the ground

to infer what temperatures must

have been in the past.

Geoengineering

• Large-scale intentional efforts to modify Earth’s climate