Exam 1 Study Guide Flashcards
What is the Big Bang Theory?
13.6 billion years ago the universe began as an infinitely hot and denser point that suddenly expanded and continues to expand
What is the Solar Nebula Theory?
4.6 billion years ago, the collapse of interstellar gas and dust created a disc-like mass, creating our solar system.
The sun was created first via nuclear fusion, then leftover material clumped together to create meteorites, asteroids, dwarf planets, moons, and planets.
How is the Earth compositionally layered?
- The core: Iron-nickel alloy
- The mantle: Olivine
3: The Crust:
- Continental: Granitic Rocks
- Oceanic: Basalt
How is the Earth physically/mechanically layered?
Lithosphere: Crust and upper mantle
- solid and rigid
Asthenosphere: Upper mantle
- partially molten and weak
Mesosphere: lower mantle
- solid that can flow
Outer core: liquid
Inner core: Solid
What is Continental Drift?
A theory put forth by Alfred Wegener in 1912; there once was a supercontinent, Pangea, and it began to split and drift apart during the Mesozoic era.
What were the key findings of seafloor spreading?
- The ocean floor is more rugged than originally thought
- Major ocean basins have a mid-oceanic ridge system
- Discovered trenches and rift valleys (spreading center) - The ocean floor is completely regenerated every 200 million years
- Fractures from spreading allow injections of magma into rift valleys (becoming new oceanic crust)
- Sediments settle in deep ocean trenches
- Oceanic crust falls into the mantle and is reabsorbed
What were the key findings of Paleomagnetism?
- Paleomagnetic reversals
- Symmetrical patterns of reversals
- Further proved seafloor spreading
What were the key findings of seismic surveys?
- Confirmed sediment thickness near continents and thinness near the ridge crest
- The oceanic crust is thin and mostly composed of basalt
What evidence was gleamed from mantle plumes and hotspots?
- As a plate moves over a hotspot, a chain of volcanoes form
- The age of each volcano indicates how long it has been since it was over the mantle plume
What is a divergent boundary?
When two plates move away from each other
Result: Upwelling of hot material from the mantle creates new seafloor.
Features:
- Subduction zones: Trenches & rifts/rift valleys/ fault zones, earthquakes and volcanoes
What are the two types of divergent boundaries?
Oceanic-Oceanic:
- Features:
+ Mid-ocean ridge along it
+ Faulting and Earthquakes
+ Volcanoes (new ocean crust created)
+ Subduction zones
Continental Rifts:
- Features:
+ Rift valley
+ Volcanoes present
+ Subduction zones
What is an example of an oceanic-oceanic divergent boundary?
East Pacific Rise
What is an example of a Continental Rift?
Rio Grande Rift
East African Rift Valley
Basin and Range USA
Red Sea Rift
What is a convergent boundary?
Two plates move toward each other.
- Two Possible Results:
+ Subduction under another plate
+ Creation of mountain belts
- Features:
+ Earthquakes
+ Volcanoes
+ Trenches and rift valleys
What are the 3 types of convergent boundaries?
Oceanic-Oceanic: One plate sinks into the asthenosphere
- Features:
+ Volcanic arc
+ Back arc
+ For arc
+ Deep ocean trenches
+ Subduction zones
Oceanic-:Continental: Oceanic plate subducts to continental
- Features:
+ Subduction zones
+ Continental volcanic arc
Continental-Continental: Netiher plate can subduct due to buoyancy
- Features:
+ Earthquakes
+ Mountain belts (no volcanoes)
+ Sutures (where continents collide)
+ Fold and thrust belts (thick sequences of sedimentary rock)
