Studied by 105 peopleRelative dating
is the process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages
○ Stratigraphy
the study of rock layer and their relationships to each other within a specific area.
○ Superposition
in an undisturbed sequence of strata, the rocks on the bottom are older than the rocks on top
○ Original horizontality
layered rocks are generally laid down flat at their formation
○ Lateral continuity
layered rocks can be assumed to continue if interrupted within its area of deposition
○ Cross cutting relationships
a geological object can not be altered until it exists, meaning, the change to the object must be younger than the object itself
○ Inclusions
when one rock formation contains pieces or inclusions of another rock, the included rock is older than the host rock
○ Fossil succession
fossils that correlate to the units of geologic time scale. A
Absolute dating
is quantitate method of dating a geological substance to a specific amount of time in the past
○ Radioactive decay
unstable isotopes spontaneously decay over time releasing subatomic particles or energy. When this occurs, an unstable isotope becomes a more stable isotope of another element.
○ Half-life
the calculated amount of time that half of the mass of an original (parent) radioactive isotope breaks down into a new (daughter) isotope
What is the Rp, Sd, and ratio for 1 half-life
50 50 1:1
What is the Rp, Sd, and ratio for 2 half-life
25 75 1:3
What is the Rp, Sd, and ratio for 3 half-life
12.5 87.5 1:7
What is the Rp, Sd, and ratio for 4 half-life
6.25 93.75 1:15
Angular Unconformity
where sedimentary strata are deposited on a terrain developed on sedimentary strata that have been deformed by tilting, folding, and/or faulting. So that they are no longer horizontal
Disconformity
where is a break or stratigraphic absence between strata in an otherwise parallel sequence of strata
Nonconformity
where sedimentary strata are deposited on crystalline (igneous or metamorphic) rocks.
Earth’s primitive atmosphere
which consisted mainly of H2O vapor and CO2, formed by outgassing. Gases trapped in the planet’s interior are released by volcanic eruptions
200,000 years ago
Human voice box evolves and we can speak coherent words. Allows us to communicate with other humans and information can be shared between individuals
7 mil years ago
Large abundance and forming of grass Evolved to walking on two legs, standing on two feet, allowed us the use of our hands
2.6 mil years ago
Stone age - Hominids began to break rocks to build hammers with a cutting edge Started to consume more calories which led to bigger brains
Paleozoic - 541 - 251.9 mil. years
Early shelled organisms, primitive fish First land plants, forests (evergreens), amphibians First reptiles, abundance of sharks, coal-forming swamps
Mesozoic 251.9 - 66 mil. years
Flying reptiles, first dinosaurs; first mammals Dinosaurs diverse and abundant, earth flowering plants, placental mammals
Big Bang
This provided the elements, along with material from former stars, to form the solar system. As material collected, high velocity impacts of matter, called planetesimals, caused Earth’s temperature to increase
Hydrogen
the element that makes up everything
Moon
keeps Earth steady and tilted on its axis. Makes seasons and stable climate
Stress
force applied to an object, typically dealing with forces within the Earth
Tensional
stresses that pull objects apart into a larger surface area or volume; stretching forces. Divergent plate boundary Resulting strain: Plastic - stretching and thinning Fault type: normal
Compression
stresses that push objects together into a smaller surface area or volume; contracting forces. Convergent plate boundary Resulting strain: Elastic - shortening and thickening Fault type: reverse
Shear
stress within an object that causes a side-to-side movement within an internal fabric or weakness. Transform fault boundary Resulting strain: Brittle - tearing Fault type: strike-slip
Deformation
A strain that occurs in a substance in which the item changes shape due to a stress.
Elastic deformation
is strain that is reversible after a stress is released.
Ductile deformation
A bending, squishing, or stretching style of deformation where an object changes shape smoothly. Occurs when enough stress is applied to a material that the changes in its shape are permanent, and the material is no longer able to revert to its original shape.
Folding
layers of rock that are curved or bend by ductile deformation
Axial planes
dividing two - dimentional line between the two sides of a fold
fold axis
the line along which the bending occurs and is where the axial plane intersects the folded strata
symmetrical folds
have a verticle axial plane and limbs ahve equal but opposite dips
asymmetrical folds
have dipping, non-vertical axial planes, where the limbs dip at different angles
anticline
A-shaped folds that are convex-upward in shape the oldest rock strata in the center, younger on the outside
Synclines
Trough-like, or U shaped, folds that are concave-upward in shape. They have beds that dip down and in toward the central fold axis. Older rock is on the outside of the fold and the youngest rock is inside of the fold axis.
Normal faults
move by a vertical motion where the hanging-wall moves downward relative to the footwall along the dip of the fault. are created by tensional forces in the crust. occur at divergent plate boundaries, where the crust is being stretched by tensional stresses
Reverse faults
compressional forces cause the hanging wall to move up relative to the footwall. Thrust faults carry older rocks on top of younger rocks and can even cause repetition of rock units in the stratigraphic record. Convergent plate boundaries with subduction zones
Strike-slip faults
have side-to-side motion. are most commonly associated with transform plate boundaries and are prevalent in transform fracture zones along mid-ocean ridges. Fault blocks on either side of the fault do not move up or down relative to each other, rather move laterally, side to side. Is determined by an observer standing on a block on one side of the fault.
Earthquakes
are felt at the surface of the Earth when energy is released by blocks of rock sliding past each other, i.e. faulting has occurred. Occur along active plate boundaries. Intraplate earthquakes (not along plate boundaries) occur and are still poorly understood. Body waves include primary (P) waves and secondary (S) waves.
P waves
Are the fastest body waves and move through rock via compression, very much like sound waves move through air. Rock particles move forward and back during passage enabling them to travel through solids, liquids, plasma, and gases.
S waves
travel slower, following P waves, and propagate as shear waves that move rock particles from side to side. Because they are restricted to lateral movement, can only travel through solids but not liquids, plasma, or gases.
Surface waves
Are produced when body waves from the focus strike the Earth's surface. Surface waves travel along the Earth's surface, radiating outward from the epicenter. take the form of rolling waves called Raleigh Waves and side to side waves called Love Waves
Raleigh Waves
Surface waves that have a up and down motion
Love waves
Surface waves that have a side-to-side motion
Wave arrival times recorded on seismographs at multiple stations
seismologists can apply triangulation to pin point the location of the epicenter of an earthquake.
By comparing data from multiple seismographs
scientists can map the properties of the inside of the Earth, detect detonations of large explosive devices, and predict tsunamis.
Shaking
is more severe closer to the epicenter. The severity of shaking is influenced by the location of the observer relative to epicenter. direction of rupture propagation and path of greatest rupture.
Climate
long term averages and variations within the conditions of the atmosphere. Defined using Koeppen System. Uses monthly average temperature and precipitation associated with different types of vegetation
Weather
current conditions within the atmosphere
The gasses that are part of the Earth
which are mainly nitrogen and oxygen - 78% nitrogen - 21% oxygen - 1% argon
Troposphere
Permanent gasses. Gasses whose proportions stay constant
Greenhouse effect
Gases that are responsible for warming and cooling the planet. Is a natural and necessary process. Earth would be 33 degreases colder without it. All surface water would be frozen. Little life would exist. Natural effect is from water vapor.
Milankovitch cycles
Natural changes in Earth’s Orbit
The causes of long-term climate changes
Changes in oceans circulation. The slow movement of the continents. Variations in the shape of Earths orbit. Changes in the angle of Earth's tilt (the range of temperatures throughout the year)
The theory of Anthropogenic Climate Change
humans are causing most of the current climate changes by burning fossil fuels such as coal
Note
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