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Time – deformation/strain rate:the faster the strain rate, the more susceptible a rock is to fracture -Composition:the mineralogical composition and water content of a rock determines its strength Folding:gradual movement, involving ductile deformation under compressive forces, leads to bending or folding of the crust -Folding is the most common form of deformation of layered rocks, its most typical manifestation is in mountain belts. -Hinge: a line where the curvature is greatest -Limbs:less curved “sides” of a fold -Axial plane:connects hinges of successive layers -Plunge:angle between the fold axis (or hinge) and the horizontal -Folds do not continue forever. Their ends die out like the wrinkles on a piece of cloth Monocline: a fold that looks like a carpet draped over a stair step Anticline: a fold that looks like an arch. The limbs dip out and away from the hinge Syncline: a fold that opens upward like a trough. The limbs dip inward and toward the hinge Anticlines and synclines are usually paired Dome and basin formation: a fold with an overturned bowl is called a dome, whereas a fold shaped like a right-side-up bowl is called a basin. A craton consists of crust that has not been affected by orogeny for a long time, typically 1 billion years. Hence, they are cool, strong and stable. Stratigraphy:the study of strata -Prior to the discovery of radioactivity and the development of the technology of radiometric dating, geologists had no precise method of absolute dating and had to rely solely on relative dating.
-Relative dating:rocks are placed in their proper sequence or chronological order Relative age:the principle of original lateral horizontality -Sedimentary layers are generally deposited in a nearly horizontal position Younger features cut across older features. Faults, dikes, erosion, etc must be younger than thematerial that is faulted, intruded, or eroded. Sediments in the ocean generally accumulate without interruption for millions or tens of millions of years—conformable -Hiatus: lapse of time recorded by an unconformity-In contrast, on the continents, sedimentation is disrupted periodically by environmental changes that lead to intervals of erosion or non-deposition—unconformities An unconformityis a time gap in the rock record, from non-deposition or erosion. There are 3 types of unconformities: angular unconformity, nonconformity, disconformity. Angular unconformities represent a huge gap (hiatus) in geologic time. Horizontal marine sediments may be deformed by orogenesis. Then, the mountains may be completely removed by erosion. After a renewed marine invasion, a new generation of horizontal sediments are deposited. Nonconformity: sedimentary rocks overlying partially eroded intrusive igneous or metamorphic rocks. Some of the igneous and metamorphic rock is eroded Disconformity: periods of non-deposition or erosion -Following a regression (sea level drop), no new sediment will accumulate and some of the pre-