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37 Cards in this Set
- Front
- Back
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What is the definition for mountains?
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An area with high elevation or rugged relief indicating tectonic force has reshaped the land
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What happen to the roots in mountains as erosion occurs?
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The deep roots and as they erode they rise back up
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What are the characteristics of volcanic mountains?
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Contain uplifted sedimentary rock, the magma injection stays in rocks along the plate edge or a hot spot
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How do complex mountains form?
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From folded, faulted and some volcanic compression of continental mass due to plate collision.
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What is an example of complex mountains?
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Appalachians and the Alps
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Define folds.
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flat-lying sedimentary and volcanic rocks are often bent into a series of wave-like undulations called folds
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What are the two most common types of folds?
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Anticlines and Synclines
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when do Folds occur?
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When stress is applied slowly to rock
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What is an anticline?
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formed by up folding or arching of rock layers
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What is a syncline?
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A syncline fold is a downfold or form troughs
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What is similar about the anticline and syncline folds?
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They can both plunge because axis of the fold penetrates into the ground
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What happens to folds when they erode?
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They form a series of ridges, such as basins where older igneous and metamorphic rock can be exposed
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what are faults?
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fractures in the crust along which great displacement has occurred
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What is a dip-slip fault?
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The movement is primarily parallel to the inclination, or dip, of the fault surface
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What are some types of dip-slip faults?
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Normal, reversal and thrust faults
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How can a dip-slip fault be a normal fault?
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When the hanging wall block moves down relative to the footwall block of the mountain
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Where do normal faults take place?
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Common at spreading centers where plate divergent occurs
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What kind of forces pull the crust apat?
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Tensional forces, either by uplifting or by opposing horizontal forces
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What are reversal and thrust faults?
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The hanging wall block moves up relative to the footwall block
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How do reverse and thrust faults occur?
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from strong compressional stresses, here crustal blocks are displaced towards one another, with the hanging wall being displaced upward relative to footwall
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where are thrust faults most common?
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Most abundant in subduction zones and other convergent boundaries
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What is a strike-slip fault?
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their displacement is horizontal and parallel to the trend.
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What is the biggest difference about a strike-slip fault?
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They are much larger and you can notice them from a greater distance, they have a zone of roughly parallel structures
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When are strike-slip faults first noticed?
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After surface ruptures that produce earthquakes
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Where do the majority of mountains form and which are they?
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The Appalachians, Alps and Himalayas form in compressional environments
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What else produces the uplift and formation of topographic mountains?
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Continental rifting
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What are the mountains known as that are formed by continental rifting?
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Fault-block mountains
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What are fault-block mountains?
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They are bounded by high-angle normal faults that gradually flatten with depth
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What do the fault-block mountains form in response to?
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To broad uplifting, which causes elongation and faulting
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What are some types of fault-block mountains?
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The Sierra Nevada in California and the Grand Tetons in Wyoming
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How are both the two fault-block ranges faulted?
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Along their eastern flanks, that were uplifted as the blocks titled downward to the west
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What is the cause for mountains standing high above surrounding terrain?
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Due to crustal thickening as well as the earth's less dense crust that floats on top of the denser and deformable rocks of the mantle
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What is isostasy?
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The concept of the floating crust in a gravitational balance
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What do compressional mountains have?
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Buoyant crustal roots that extend deep into supporting material below
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What is the isostatic adjustment?
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The top and bottom of the supporting material establish a new level of gravitational equilibrium
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Describe the isostatic adjustment.
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When weight is added to the crust, it will respond by subsiding and when weight is removed, the crust will rebound. (Which aids to the stability of mountains)
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What keeps mountains like the Himalayans standing high?
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The horizontal compressional forces are greater than gravitational forces which keeps them from completely eroding away
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