Geol 1003 Test 1

Three reasons Earth has life

Distance from sun, atmosphere, surface water

Biosphere

Plants and Animals

Hydrosphere/Cryosphere

Water/Ice

How much of Earth is covered by water? How much by land?

70%, 30%

Lithosphere (Geosphere)

Solid Earth

Atmosphere

Envelope of gas that surrounds Earths

Give an example of how these sphere’s are connected

Watercycle & Volcanic Eruption

Uniformitarianism

The present is the key to the past (allows us to study past and predict future)

Are processes on Earth likely to significantly change through time?

No

What was the past accepted idea about Earth science?

Catastrophism

Catastrophism

All of the geologic record is recordings from catastrophic events (Meteroites)

Was was John Hutton’s hypothesis about geologic processes?

They are really slow, but there is plenty of time for creating the rock record without soley relying on catastrophic events

How old is Earth?

4.6 Billion years old

Rocks are created by what?

Amalgamation of 2 or more minerals

What are the building blocks of rocks?

Minerals

Mineral

Naturally occuring, solid, particular chemical composition, characteristic internal structure

Three types of rocks

Sedimentary, Metamorphic, Igneous

What are Nicolaus Steno’s 3 principles of stratigraphy (layers of rock)

Superposition, Original Horizontality, Lateral Contninuity

Superpostion

Younger rocks exist on top of older rocks

Original Horizontality

Rocks are deposited flat, if they are tilted then they were deformed

Lateral Continuity

Rocks are deposited laterally until the edge of a basin

Intrusive Relationships

Intrusions are younger than the rocks they intrude

Cross cutting relationships

Faults (or any cross cutting outcrops) are younger than the rocks they cut

Principle of Inclusions

All particles contained within a rock are older than the rock

Principle of Fossil succesion

Fossils are preserved in the order in which they lived

Which rock type is best used for radiometric dating?

Igenous rocks because of radioactive decay

“Marker” Layers

Special layers that we know the age of (e.x. layer of iridium from meteorite)

Continental shelf

Part of the continental margin which is between the shoreline and the shelf break OR where there is no noticeable slope between the shoreline and the point where the water depth is ~100-200 m

At what margin are continetal shelfs most likely to form at?

Passive because there is no plate boundary. Additionally this is better for oil and gas drilling)

How did petroleum and nautral gas form?

1. Tiny marine and plant animals died, were buried, and covered by sediments

2. Over millions of years sedimentation occured buring the remains deeper. Enormous heat and pressure turn the remains into oil and gas.

3. Oil and gas contined in reservoirs (usually sandstone)

Oil and Gas formation depend on what two things?

Sedimentation and Abundance of marine life

What do we use to determine relative ages?

Geologic principles (superposition, intrusive relationships, fossil succesion)

What do we use to determine absolute ages?

Radiometric ages

How do we create the first geologic time scale?

By correltating fossils and evolution across the earth, eventually dates were added after procces like radiometric dating came about.

What are some examples of the geosphere (lithosphere)?

The crust, mantle & core; the Lithosphere & Athenosphere; Tectonic activity; Plate boundaries

Hydrosphere/Cryosphere

Water cycle

How is water on earth stored?

97% in oceans, 1.8% glaciers/rivers/lakes/atmosphere

Directional change

Progessive, systematic/ can never return to a past condition

Examples of directional change

Evoltuion and Earth’s temperature

Eposidic changes

Occur in “pulses”

Examples of episodic changes

Sedimentation, volcanism, mass extinctions

Transipiration

Water enters the atmosphere through plants

Evaporation

Water enters the atmosphere not through biologic material

What are some common features of a subduction zone?

Trench, accretionary wedge, volcano, mtn building/folding, thrust belt, compression & earthquakes

What are used to create divisions in the timescale?

Major changes in the biosphere

Unconformities

Represent a time of erosion or nondeposition

What are the 3 types of unconformities?

Nonconformity, Angular unconformity, disconformity

Nonconformity

Sedimentary rocks deposited on crystalline rocks

Angular unconformity

Rocks deposited on tilted rocks (rocks below deformed before rocks above were deposited + requires period of erosion)

Disconformity

Parallel sedimentary rocks with a gap in time betwen layers

What is the oldest undisputed fossil and how old is it?

Stromatilite, 3.5 billion years old

What is the oldest well understood fossil and how old is it?

Ediacaran fauna (marine based), 600 million years old

Properties of Index fossils

Lived for a short time period, geographically widespread, easy to ID, numerous

Biozone

Stratigraphic interval that can be defined on the basis of a specific fossil

What are some biozone fossils?

Ammonites and Formas (calcium carbonate shells)

Half-Life

Time it takes for ½ of parent molecules to decay into daughter molecules

What is a key mineral for decay rating?

Zircon because it is a common mineral in all rocks

Why is carbon dating not useful for rocks, and what is it useful for?

Because carbon is not a common component of most rocks. It is use for archaeological ages

What is the radioactive proces in rocks?

1. Parent atoms live in a melt. 2. As magma cools minerals grow. 3. Rock (minerals form) and radioactive decay begins.

The radioactive prcoess gives what?

The age a mineral cooled from a melt

In an igneous rock are the minerals and rock the same age? Explain

Yes, because the rock and mineral form at the same time so they have the same age

In a sedimentary rock are the minerals and the rock the same age? Explain

No, because the grains are older than the rock, there are a variety of grains and ages so the rock must be younger than the age of the grains

List our current, Eon, Era, Period, and Epoch

Phanerozic, Cenozoic, Quanternary, Holocene

How many years ago did the cenozoic era begin?

66 million years ago

What is the age range for the mesozoic era?

Started 252 million years ago and ended 66 million years ago

What is the age range for the paleozoic era?

Started 541 million years ago and ended 252 million years ago

Who came up the 1st geological map and started naming time periods?

William “Strata” Smith

The precambrain eons makes up how much of Earth history? How about the phanerozoic eon

88%, 12%

What eons are included in the precambrian grouping?

Hadean. Archean, Proterozic

What dominates the paleozoic Era

Marine life dominated, first appearance of land plants (conifers/spore plants)

What dominated the mesozoic Era

Reptiles and flowering plants dominated

What dominates the cenozoic Era

Mammals and grasses dominated

List some of the beginning conditions of Earth

Extreme heat from Earth’s formation, continued bombardment of Earth by meteroites, and constant remelting of Earth’s surface

How long and in what age did the oceans form?

By 4.3 million years ago, in the Hadean eon

Where are the potential areas for life on early Earth?

Deep in the crust and in hydrothermal vents

Why is early Earth challenging to study?

Because of there are minimal rocks from the Hadean and Archean eons

What were Earth’s earliest organisms?

Extremophiles

Extremophiles

Lived in harsh conditions like hydrothermal vents and salt marshes, were chemosynthesizers, and belonged to the Archean domain

Chemosynthesizers

Create nutrients by chemical reactions

3 Domains of organisms

Bacteria (Prokaryotes), Archea (Prokaryotes), and Eukaryotes

Prokaryotes

Structurally simples, single celled, small in size, no nucleus or organelles in their cells, earliest lifw

How did stromatolites get their energy?

Photosythesis

How did stromatolites form?

1. Algal mat of cyanobacteria + carbonate sediment 2. Cyanobacteria grows upwards through sediment for sunlight 3. Cyanobacteria sitting on layers of limestone = stromatolites

Give the time period of Banded Iron formations

3.8-2.0 Billion years ago

What makes up banded iron formations?

Chert + Iron oxide

What did Banded Iron Formations indicate about oxygen?

Much of it was in the ocean rather than the atmosphere

What did banded iron formations give way to and why?

Red beds, because the amount of oxygen increased in the atmosphere (oxidation occurs on the surface rather than in the ocean)

Eukaryotes

Appeared 2.7 Billion years ago, cells w/ nuclei and DNA in nucleus, organelles, cells are larger, formed because of O2 in the atmosphere

What do the oldest known multicellular eukaryotes resemble?

Algae resembling seaweed

Grypania

Oldest known multicellular eukaryote, reproduced asexually

What process helped eukaryotes evolve?

Symbiosis: 1. Protist evolved chromosomes 2. Absorbed aerobic bacteria became mitochondria 3. Absorbed cyanobacteria became chloroplasts

List the kingdoms in eukaryotes

Protista (Doesnt fit well in the other kingdoms), Plantae, Fungi, Animalia

When did the animalia kingdom first appaear? (When did the first animals appear)

Ediacaran time

What is the earliest known animal?

Dickinsonia

When do the first trace fossils appear?

570 million years ago

What were the 1st organisms?

Archaea

Cambrian Explosion

Huge uptick in diversity of marine organisms and 1st organisms with hard parts

Why did marine invertebrates develop shells?

To protect from perdators and to protect from the physical/chemical changes in the ocean

Did plants or animals get on land first?

Plants, they were Bryophytes

What were the first multicellular plants?

Algae