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34 Cards in this Set
- Front
- Back
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Mountain Building
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elevated belt produced by deformation of earth's crust.
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Deformation
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change in volume or shape of rock body.
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What causes deformation?
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stress
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Compressive Deformation
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squeeze and shorten rock body.
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Tensional Deformation
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stretch and elongate rock body.
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Shear Deformation
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sliding motion
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Plate Margins
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1. divergent: tensional
2. convergent: compressional 3. transform: shear |
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Brittle
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fracture, low pressures and temperatures, near surface.
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Ductile
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plastic, flowing, high pressure and temperatures, deep.
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Folds
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wavelike undulations, generally caused by compression.
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Anticlines
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upfolds (arches)
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Synclines
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downfolds (troughs)
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Joints
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fractures with out displacement.
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Faults
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fractures with displacement.
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Two types of faults
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dip slips and strike slips
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Fault Block
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tensional stress, ex: southwest US and east Africa
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Domes
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broad arching, batholith may arch overlying strata, ex: Black Hills, SD
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Folded (Belts)
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most common
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Oceanic Oceanic
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ex: Japan, Aleutian Islands, accreationary wedge, volcanic islands.
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Oceanic Contental
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ex: west coast South America, northwest US.
- accretionary wedge, volcanic mountains on land. |
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Continental Continental
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ex: Himalayas
- Subduction precedes continental collisions. |
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Convergent plate boundary
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Two tectonic plates or pieces of lithosphere move toward one another and collide
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Divergent plate boundary
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Two tectonic plates pull away from each other
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Transform boundary
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Two tectonic plates slide passed one another
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Convection
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The driving mechanism of the mantle
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What are the two kinds of Geological time?
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Relative - shows the sequence of events
Absolute - show the age of the rock |
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Principles of geologic time:
Original Horizontality |
all layers of sediment (strata) were at one point horizontal until displacement took place
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Principles of geologic time:
Superposition |
If no displacement has taken place the youngest rocks will be on the top with every layer beneath it getting older
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Principles of geologic time:
Unconformities |
Break in the rock record, like missing pages in a book.
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Principles of geologic time:
Cross-cutting relationships |
any feature such as a fault or igneous intrusion must be younger
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Principles of geologic time:
Inclusions |
Pieces contained within other rocks are older
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Absolute dating uses...
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a masspectrometer to measure levels of radioactive isotopes in the rocks
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Parent isotopes...
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degrade into daughter isotopes
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3 assumptions of absolute time:
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The rock decays at an exponential rate
no daughter is present when the rock is formed It is with in a closed system |
