Studied by 29 people
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
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