Term
|
Definition
| The science that pursues an understanding of planet Earth |
|
|
Term
|
Definition
| Examines the materials composing Earth and seeks to understand the many processes that operate beneath and upon its surface |
|
|
Term
|
Definition
| means that dates are placed in their proper sequence or order |
|
|
Term
|
Definition
|
|
Term
|
Definition
mass/volume
Usually in grams per cubic centimeter gm/cc |
|
|
Term
|
Definition
| Solid earth, oceans and atmosphere have layers based upon density differences, they are density stratified |
|
|
Term
|
Definition
| Big bang: expansion of the universe-first stars and galaxies formed. |
|
|
Term
|
Definition
| Cloud of gas and space dust (nebula) began to contract forming Proto-planets |
|
|
Term
|
Definition
| The earth's oceans were essentially in place. Oldest rocks from Canada are of this age. |
|
|
Term
|
Definition
| Oxygen production greatly accelerated from green plants. |
|
|
Term
|
Definition
| First multi-cellular organisms appear |
|
|
Term
|
Definition
|
|
Term
|
Definition
• Assumes a flat, disk shape with the protosun (pre-Sun) at the center
• Inner planets form from metallic/rocky substances
• Larger outer planets began forming from fragments of ice (H2O, CO2, and others) |
|
|
Term
|
Definition
• Initially homogenous
• Larger in size than today’s Earth
• No continents or oceans, or life
• Denser materials sank to the center
• Early crust began to form |
|
|
Term
|
Definition
| Produced large volumes of water and formed earths primitive atmosphere of carbon dioxide, nitrogen, methane, and ammonia. |
|
|
Term
|
Definition
• Late 1700’s “the age of modern geology “ James Hutton
• The present is the key to the past
• The way to understand the Earth's history is by comparing to current processes and events
• Most geologic changes occur slowly over long periods of time. |
|
|
Term
|
Definition
• Atmosphere
• Hydrosphere
• Biosphere
• Solid Earth |
|
|
Term
|
Definition
Continents:
• Stable interior
• Mountain belts
Ocean basins
• Continental margins
• Deep-ocean basins |
|
|
Term
|
Definition
Solidification of magma (at depth) and lava (on surface)
Ex: granite and basalt |
|
|
Term
|
Definition
Derived from weathering of pre-existing rocks. Often contain fossils and indicative internal structures.
Ex: sandstone and limestone |
|
|
Term
|
Definition
Formed by “changing” pre-existing igneous, sedimentary or other metamorphic rocks
• Driving forces are increased heat and pressure.
Ex: gneiss and marble |
|
|
Term
| How do we know the structure of the earth? |
|
Definition
• Seismic (earthquake) waves
• Gravity measurements
• Magnetic measurements |
|
|
Term
|
Definition
• Earthquake waves that traveling through the earth
• two types of waves: surface waves and body waves
• surface waves travel on the surface
• body waves travel through the earth
• there are two main types of body waves: P and S waves |
|
|
Term
|
Definition
Primary
Compressional (Parallel)
Faster
Solids, liquids, and gas |
|
|
Term
|
Definition
Secondary
Shear(Perpendicular)
Slower
Solids only |
|
|
Term
|
Definition
| P and S waves both go through solids. S waves do not go through non-solids, so only P waves are received on the opposite side of the earth. |
|
|
Term
| What can P and S wave data tell us? |
|
Definition
1. Parts of the earth are not solid.
2. The depth and location of an earthquake (EQ)
3. The relative strength of an EQ
4. The average density of earth.
5. The density of each layer in the earth. |
|
|
Term
|
Definition
| tell us that there must be denser material deeper in the earth through the gravity formula |
|
|
Term
|
Definition
• Formed from convection in the liquid outer core
• Tells us about the composition and physical properties in the interior of the Earth.
• There must be significant amounts of iron for earth to have such a strong magnetic field. |
|
|
Term
| Earth's layers defined by composition |
|
Definition
|
|
Term
|
Definition
• Composed of light silicates rich in aluminum.
• Comparatively thin outer skin that ranges from 3 km at the oceanic ridges to 70 km in some mountain belts.
• Separated into thin oceanic (3.0 gm/cc) and thicker continental crust (2.7 gm/cc) |
|
|
Term
|
Definition
• Composed of heavier silicates rich in iron and magnesium
• Large portions can flow slowly and are near melting. |
|
|
Term
|
Definition
• An iron-nickel rich sphere
• Outer core is liquid, convection here sets up earth’s magnetic field
• Inner core is solid and very dense |
|
|
Term
| Layers defined by physical properties |
|
Definition
Lithosphere
Asthenosphere
Methosphere (lower mantle)
Outer core
Inner core |
|
|
Term
|
Definition
Mohorovic discontinuity
Core mantle boundary
Lehman discontinuity |
|
|
Term
Plate Tectonics
1600 - 1700's |
|
Definition
It was noticed that charts of land masses in the new world "fit" together like a puzzle.
Geologic and fossil trends indicated that some land masses which are now separated may have been together at some point in time.
Nobody could provide a mechanism for the continents to move. |
|
|
Term
|
Definition
1912
German with PhD is astronomy and interest in meteorology.
Proposed the concept of continental drift in a lecture. |
|
|
Term
|
Definition
| Name given by Alfred Wegener for original land mass |
|
|
Term
| What did Alfred Wegener propose about the original landmass? |
|
Definition
| continents started moving about 200 million years ago (MYA) and they are still moving. This is amazing because it is pretty accurate. |
|
|
Term
| What were Alfred Wegeners conclusions about continental drifting based on? |
|
Definition
| Fossil evidence of Mesosaurus (reptile), Glossopteris (plant) and the present distribution of plants and animals especially marsupial mammals. |
|
|
Term
| What did geophysicists Wadati and Benioff delineate in the 1940's? |
|
Definition
| They plotted deep earthquakes and delineated the "Ring of Fire". |
|
|
Term
| When was radiometric age dating developed |
|
Definition
|
|
Term
| How old is the oldest continent? |
|
Definition
|
|
Term
| How old is the oldest sea floor? |
|
Definition
|
|
Term
| Who claimed that continents plowed through the oceanic crust? |
|
Definition
|
|
Term
| What did Harry Hess propose in the 1960's? |
|
Definition
| That the continents did not plow through the oceanic crust (Wegener) but were riding with the oceanic crust like a conveyor belt. |
|
|
Term
| What is the definition of Plate Tectonics? |
|
Definition
| A theory that states that the earth's solid outer shell (lithosphere) broken into "plates" can move relative to each other while sitting over a plastic, non-solid layer called the astenosphere. |
|
|
Term
| What is thought to be the driving force of plate tectonics? |
|
Definition
| Convection in the asthenosphere |
|
|
Term
| Which boundary is the most important for plate tectonics to occur? |
|
Definition
| The lithosphere/asthenosphere boundary |
|
|
Term
| What happens in plate tectonics where the solid lithosphere plates meet? |
|
Definition
| We see the most volcanic and seismic activity. |
|
|
Term
| What is the evidence for plate tectonics? |
|
Definition
A) Continental drift
B) Plate boundaries
C) Hotspots |
|
|
Term
| What is the evidence for continental drift? |
|
Definition
1. the shape of the continents
2. fossil evidence
3. geologic features (old mountain ranges spanning contenental boundaries)
4. Paleomagnetism
5. The sedimentary rock record |
|
|
Term
| What are the three types of plate boundaries? |
|
Definition
1) Divergent (pulled apart, tensional force)
2) Convergent (pushed together, compressional force)
3) Transform (sliding past or rotational) |
|
|
Term
| What are the two signs of divergent plate boundaries? |
|
Definition
1. Seafloor spreading
2. Continental rifting |
|
|
Term
| What is the process of seafloor spreading? |
|
Definition
Tensional forces pull oceanic crust apart.
Mid oceanic ridge forms
Lava rises, new seafloor surface
Older is more dense, gets pulled away from ridge |
|
|
Term
|
Definition
| Spreads faster and is less steep |
|
|
Term
|
Definition
| is steeper and spread slower |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| How does continental rifting occur? |
|
Definition
Continental crust pulls apart
Large amount of sediment produced
Forms lakes and rivers, finally an ocean |
|
|
Term
| What is an old continental rift? |
|
Definition
| Africa pulling apart from SA |
|
|
Term
| What are two present continental rifts? |
|
Definition
1. Red Sea
2. East Africa Rift System
3. Djiboti |
|
|
Term
| What are the features of convergent plate boundaries? |
|
Definition
• Plates move together and collide so you have compressional forces
• Active margins: mountain building, earthquakes, and andesite (explosive) volcanoes.
• Most dangerous type
• Earthquakes up to 9.5 in subduction zones
• Andesite volcanoes: very explosive
• Tsunami potential where you have subduction. |
|
|
Term
| What are the three types of convergent plate boundaries? |
|
Definition
1. Subduction of OC beneath CC
2. Subduction of OC beneath OC
3. Continental collisions, CC colliding with CC |
|
|
Term
| What happens in the subduction of OC beneath CC? |
|
Definition
• Denser, thinner OC is pushed or subducted beneath less dense and more buoyant CC.
• Called a continental volcanic arc.
• Deep and shallow (tsunami potential) focus earthquakes, the largest ever 9.5 magnitude in Peru/Chile Trench in 1960
• Andesite (explosive) volcanoes, like the Cascade Range: Mt. St. Helens etc.
• Deep trenches form around continents (more on trenches later). Especially when far away from spreading centers.
• Reduces amount of (destroys) OC.
• Rates up to 15 cm/yr in the active margins of the Pacific Basin |
|
|
Term
| What happens in the subduction of OC beneath OC? |
|
Definition
• Many similar features as above.
• Denser, older, cooler OC is pushed or subducted beneath less dense, warmer, younger OC.
• Forms island volcanic arcs
• Deep and shallow (tsunami potential) focus earthquakes
• Volcanoes not as explosive as above with OC/CC, as there is no mixing of CC rocks (called granites). Mostly basaltic.
• Reduces amount of (destroys) OC. |
|
|
Term
| What happens in a Continental Collision? CC colliding with CC? |
|
Definition
• Neither of the CC are subducted,
• Both are very buoyant and want to "float" or ride high.
• This is where you form the very large mountain chains.
• Mountain building
• Earthquakes |
|
|
Term
| What are the three types of transform boundaries? |
|
Definition
1. Continental transform faults
2. Oceanic transform faults
3. Hotspots and mantle plumes |
|
|
Term
| What are the features of Continental Transform Faults? |
|
Definition
• In CC we have large destructive faults like the San Andreas.
• Magnitudes up to 8.5 have been measured.
• Rates on the San Andreas average 2-5 cm/yr or LA will be adjacent to SF in about 20 million years.
• Where these faults bend or change direction you can get local compression (and uplift) like Mt Soledad or tension (and down-warping) |
|
|
Term
| What are the features for Oceanic Transform Faults? |
|
Definition
• In OC, perpendicular to the spreading centers we have smaller transform faults.
• They have smaller earthquakes associated with them, when compared with their continental cousins.
• These faults occur where there is a bend or change in the rate of spreading along the MOR. |
|
|
Term
| What are the features of hotspots and mantle plumes? |
|
Definition
• These are hotspots beneath the lithosphere caused by rising plumes of mantle material
• Can form volcanoes on surface:
-Mostly mafic (basaltic) as these lavas are very fluid.
-Less common are felsic (rhyolitic) magmas as they are thicker and less prone to flow. |
|
|
Term
Where are the Hawaii volcanoes formed?
What type of volcanoes are they?
How long has the hotspot existed? |
|
Definition
Underneath oceanic crust,
Forms basalt (non-explosive) volcanoes,
This hotspot has existed for about 60 MY's. |
|
|
Term
Where is the Yellowstone hotspot?
What types of volcanoes?
How many times has it erupted in the last 2 million years? |
|
Definition
Underneath continental crust
Forms rhyolitic and other types of volcanoes
Has had large rhyolitic eruptions 3 times in the last 2 million years |
|
|
Term
| What drives plate motions? |
|
Definition
Convective flow in the mantle
• Slab-pull
• Ridge-push
• Convective friction |
|
|
Term
| What is the importance of plate tectonics? |
|
Definition
• The theory provides explanations for many of earth’s major processes
• The geologic distribution of earthquakes, volcanoes, and mountains
• The distribution of ancient organisms and mineral deposits
• Plate tectonics are responsible large volumes of oil and gas deposits we enjoy today. |
|
|
Term
| Which two major interior parts (not lava or magma) of the earth are non-solid? |
|
Definition
a) Asthenosphere
b) Outer core |
|
|
Term
|
Definition
| Moho stand for the Mohorovicic discontinuity. It is one of the Earth’s major boundaries which separates the crust and the mantle. First discovered in the early 1900’s by a Croatian named Andriaja Mohorovicic who interpreted the gathering speed of P waves as a change of composition beneath the Earth’s surface. |
|
|
Term
| What is the average thickness, density and rock type of continental crust? |
|
Definition
a) About 25 miles thick
b) About 2.7 g/cm3
c) Many rock types with a granitic rock called granodiorite showing up the most. |
|
|
Term
| What is the average thickness, density and rock type of oceanic crust? |
|
Definition
a) About 5 miles thick
b) About 3.0 g/cm3
c) Basalt (igneous rock) |
|
|
Term
| Describe or orign of andesite volcano. |
|
Definition
| An andesitic volcano is formed when tectonic plates produce a large amount of friction by rubbing together, generating enough heat to produce molten rock known as magma. The magma is then pushed through the earth’s surface and gradually becomes solid, forming the volcano. |
|
|
Term
| Name the three types of plate boundaries and give one common (name place/area) example location for each. |
|
Definition
a. Divergent – Iceland
b. Convergent – the Andes
c. Transform – Hawaii |
|
|
Term
|
Definition
• Consists of the crust and uppermost mantle
• Relatively cool, rigid shell
• Averages about 100 km in thickness, but may be 250 km or more thick beneath the older portions of the continents |
|
|
Term
|
Definition
• Beneath the lithosphere, in the upper mantle to a depth of about 600 km
• Behaves plastically and can mechanically detach and move independently of the lithosphere. |
|
|
Term
| Mesosphere or lower mantle |
|
Definition
• Rigid layer between the depths of 600 km and 2900 km
• Rocks are very hot and capable of very gradual flow |
|
|
Term
|
Definition
• Liquid layer
• Composed mostly of an iron-nickel alloy
• Convective flow within generates Earth’s magnetic field |
|
|
Term
|
Definition
• Behaves like a solid
• Very dense around 16 gm/cc |
|
|
Term
|
Definition
• Discovered in 1909 by Andriaja Mohorovicic
• Separates crustal materials from underlying mantle
• Identified by a change in the velocity of P waves |
|
|
Term
|
Definition
• Discovered in 1914 by Beno Gutenberg
• Based on the P-wave shadow zone
• No P waves from 105 to 140 degrees
• S waves do not travel through the outer core provides of liquid outer core below the mantle |
|
|
Term
|
Definition
• Predicted by Inge Lehmann in 1936
• Boundary between outer and inner core
• Increase in velocity from outer to inner core
• Reflection off solid inner core |
|
|
Term
|
Definition
Undergrad Yale, graduate Princeton
A professor of geology at Princeton University, was very influential in setting the stage for the emerging plate-tectonics theory in the early 1960s |
|
|
Term
| Who put the Theory of Plate Tectonics together along with Harry Hess? |
|
Definition
| Vine and Matthews (Paleomagnetism), and Tuzo Wilson (plate boundaries) |
|
|
Term
| What is an example of OC subducting beneath CC? |
|
Definition
|
|
Term
| What is an example of OC subducting beneath OC? |
|
Definition
Aleutian Islands SW of Alaska
Japan
Tonga Islands
Phillipines |
|
|
Term
| What is an example of CC colliding with CC? |
|
Definition
Himalayas (India) 45 MYA
Appalachians (East Coast NA) 350-400 MYA |
|
|
Term
| What is the general range of rates that seafloor spreading occurs? |
|
Definition
|
|
Term
| A fracture is just a _____ if it moves it becomes a _____ |
|
Definition
|
|
Term
| Continental transform faults |
|
Definition
1. Cool
2. Hard to move
3. Large EQ |
|
|
Term
|
Definition
Warm
Easy to move
Lost of small EQ |
|
|
Term
|
Definition
| Between rocky mantle and outer core. |
|
|
Term
|
Definition
P waves arrive at the seismometer first, followed by the S-wave. Once the S-wave arrives.
The difference in the arrival times of the waves is distance from earthquake |
|
|
