Mountain Building Flashcards
Result from earth’s surface behaving in brittle fashion causing it to break
Fractures
Two main types of fractures
joints and faults
Rock fractures along which there has been appreciable movement, 1 of the most common geological structures, Occur in broadly parallel evenly spaced groups
Joint
3 types of joints
columnar, exfoliation, tectonic
distinctive sets of contraction fractures that outline long polygonal columns; occurs when basalt cools down and cracks as it shrinks
Columnar Joints
Gently curved land fractures that are broadly parallel to the land surface; common in granite bodies; form due to erosional unloading
Exfoliation joints
Produced by tectonic forces that cause rocks to break in a system of regional stresses; most joints are this type
Tectonic Joints
Where do tectonic joints occurq
in areas that are being stretched compressed or sheared
Represent plane of weakness; significant movement involved
Faults
Types of Faults
DipSlip
StrikeSlip
Direction of movement is generally parallel to the dip of the fault plane
dip slip faults
Two types of dip slip faults
Normal Faults
Reverse faults
Results in tensional stresses; Headwall moves down relative to footwall; crust being extended; common in mid ocean ridges and continental rifts
Normal Fault
Headwall moves up relative to the footwall, crust is being squeezed; occur in compressional areas; crust is thickened
Reverse Faults
Low angle compressional faults merging at depth
Thrusts
