Unit 5- Class Notes and My Notes Flashcards
In what 5 ways is Earth “unique”?
1) Abundant life, including complex life forms.
2) Abundant LIQUID water (other planets and moons may have ice, but no water)
3) Large liquid Fe/No core (outer core), resulting in a magnetic field (Earth is the only one with a liquid core even though others may have iron cores)
4) Plate Tectonics (process)
5) Semi-unique: asteroid impacts–inner solar system vs. outer. Comets are a different matter.
What is the top of lithosphere controlled by?
what happened in the past (geologically)
What is the top of the lithosphere composed of?
continental crust and oceanic crust
How is oceanic crust different that continental crust?
The oceans are not merely topographically low places full of salty water. They re fundamentally different, with different (though related) geological histories.
What is the difference in the age of rocks in the continental crust and oceanic crust?
Rocks in C.C. range from Now in age, back to about 4.1 Ga. The oldest rock in the OC is only about 160 million years old.
What are the 7 geomorphic features (topography and geology) of the continual-oceanic edge?
1) shorelines
2) continual shelfs and slopes
3) abyssal plains and hills, sea mounts, and volcanoes
4) Mid-oceanic ridges and rises (MOR)–volcanoes
5) Tectonic mountain belts
6) Precambrian shields
7) continental platforms “Phanerozoic”
Continual Margin___(Atlantic) Type
passive
What is the Continental Margin Passive (Atlantic) type of oc-cc edge?
Oceanic and continual are butted together.
What is the active (pacific) type of cc-oc edge related to?
- volcanoes
- earthquakes
- subduction
- trenches
What happens at the oc-cc active type of edge?
One plate subjecting under the other plate and creates a trench which is the deepest part of the ocean
What is the deepest part of the ocean?
ocean trench (has to do with convergent plate boundaries)
What is Plate tectonics?
OC and CC in motion relative to each other
OC will always go__CC because the OC is more dense than CC…this is called?
under
-isostasy
What is a mountain?
A large rise of land, much higher than surrounding land
What is a mountain belt or system?
A region or chain of mountains
What are the 3 causes of mountains?
1) Volcanism (e.g. isolated or vol. arcs)
2) Intrusion of batholiths (least common)
3) Orogeny (materials is folded, creates fault)
What is orogeny? How long does it last?
A period of time of (or the event of) folding and faulting (lasts for about 100 Ma)
Orogeny includes___and___at depth
Metamorphism and intrusion
Orogeny results in___to form mountain belt and___of topographic surface. Isostatic___(rebound) also takes place.
- uplift
- erosion
- uplift
Which orogeny, what is slowly reduced as once deeply exposed rocks become exposed.
topography
What is orogeny related to? What location?
Related to plate tectonics, mostly at Convergent Boundaries.
What is Orogen?
A belt or region in which orogenic mountain building has taken place, over a specific time span, even if no longer mountains.
How are orogens identified?
Any mountains or high hilly area whose rocks were deformed (regional meta. locally) during a specific relatively recent time span.
A region containing deformed and meta. rocks, now fairly flat topographically because, whatever the original topography, erosion has planed the region flat and isostasy has brought upon deeply buried rocks…what is this?
orogeny over a specific time span.
Young Orogeny mostly
150
What is a young orogen?
erosion has not eroded the region flat
Ancient orogen >___Ma and up to>___Ma
150, 3500
What are shields?
- Ancient parts of continents >570 Ma
- Made of various orogens formed over ~3000 Ma
- Mostly topographically low
What is carton?
Ancient stable land (an block composed of ancient orogens).
When did the Cordilleran Mountain belt start to form?
150 ma
What caused the cordilleran Mnt. belt to form?
when two tectonic plates were coming together
What mountain belt discussed is still slightly active
1) Alpine Himalayan Belt
What is the Ring of Fire?
Volcanoes stude most of the way around the pacific ocean
How did the Ring of Fire form?
through tectonic mountain belts (orogenic process)
Orogenic Mountain belts = ___
tectonic mountain belts
Why are Ural and Appalachian mountains not high?
because of at least 250 million years of erosion
How old are areas rich in precambrian rocks?
over 1.8 billion years old
In most precambrian areas, all rocks have undergone___building.
orogenic
Every continent is made up of rocks that were once a part of an___mountain belt.
orogenic
What is a shield?
- ancient parts of continents >570 Ma (rock ages)
- made of various orogens formed over ~3000 Ma
- mostly now topographically low
What is a carton?
-ancient stable land block (composed of ancient orogens)
