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| Shows the distribution of rocks at Earth's surface. The rocks commonly are divided into mappable rock units that can be recognized and traced across the map area. This division is made on the basis of color, texture, or composition. |
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| The study of how geologic units (bodies of rock or sediment) are arranged when first formed and how they are deformed afterward. |
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| A drawing of a vertical slice through Earth, with the material in front of it removed: a cutaway view. |
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| A combination of the geologic map and cross section. It looksl ike a solid block, with a geologic map on top and a geologic cross section on each of its visible sides. |
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| The orientation of a rock unit or surface. |
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| The compass bearing (direction) of a line formed by the intersection of a horizontal plane (such as the surface of a lake) and an inclined layer (bed, stratum) of rock, fault, fracture, or other surface. |
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The angle between a horizontal plane and the inclined (tilted) stratum, fault, or fracture.
Dip direction is always perpendicular to the line (bearing) of strike. |
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| An unconformity between relatively parallel strata. |
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| An unconformity between nonparalled strata. |
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| An unconformity between sedimentary rock/sediment and non-sedimentary (igneous or metamorphic) rock. |
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| In rock units are breaks along which movement has occurred. Faults form when brittle rocks experience three kinds of severe stress: tension, compression, and shear. |
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Pulls apart causing lenghtening.
Normal Fault |
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Pushes together causing shortening.
Reverse Fault (High Angle) |
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Rocks slide past each other causing tearing and smearing.
Strike-Slip Faults |
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| Are "upfolds" or "convex folds". |
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| If the oldest rocks are in the middle. |
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| Are "downfolds" or "concave folds" |
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| If the youngest rocks are in the middle. |
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| The fold axis may not be horizontal, but rather it may plunge into the ground. |
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| The angle between the fold axis and horizontal. |
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| The trend of a plunge is the bearing (compass direction), measured in the direction that the axis is inclined downward. |
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| If a fold is tilted so that one limb is upside down, then the entire fold is called an overturn fold. |
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| Have two axial planes that separate two nearly horizontal limbs from a single, more steeply inclined limb. |
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| Are large, somewhat circular structures formed when strata are warped upward, like an upside-down bowl (dome) or downward, like a bowl (basin). |
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