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73 Cards in this Set
- Front
- Back
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Topography
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the study of the surface of the earth
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Stratigraphy
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the branch of geology concerned with the order and relative position of strata (or layers) and their relationship to the geological time scale.
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What does a topographical map do and what does it represent?
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Topographic maps show the shape of the surface of the Earth. Steepness of mountains, depth of valleys, etc. are all accounted for and represented
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Contour Lines
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lines that connect points of equal elevation. Brown on land, blue in water.
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Elevation
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the altitude of an area measured from SEA LEVEL, which is assumed to be zero
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Contour interval
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the change in elevation between two consecutive contour lines
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Indexed contour lines:
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lines that are marked with their elevation. Heavier and darker than the other contour lines. Every fifth line.
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Benchmarks
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a point on the map that is labeled with its precise elevation
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Profile
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the shape of a geographic feature from the side
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Know important rules about contour lines
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They don’t overlap except in the case of a vertical cliff; they are enclosed shapes; they are hatched to indicate depressions; if they are close together, it means they are steep; if they are far apart, it means they are flat
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Gradient
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the slope
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Low Gradient (or Relief)
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flat terrain and plains
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High Gradient (or Relief)
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steep terrain and mountainous areas
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Formula for Slope
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Elevation/Distance
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Glacier
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large, flowing masses of ice formed by buildup of snow on land
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Moraine
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a mass of rocks and sediment carried down and deposited by a glacier, typically as ridges at its edges or extremity. IT IS DEPOSITIONAL
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Erratics
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a rock or boulder that differs from the surrounding rock and is believed to have been brought from a distance by glacial action. THEY ARE DEPOSITIONAL
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Verves
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annual layers that indicate a pattern of deposition. Verves are comprised of alternating layers CLAY and SILT.
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U-shaped valleys
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heavy erosion creates valleys with a U-shaped profile. THEY ARE EROSIONAL
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Hanging valleys
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when one lobe of a glacier cuts across an existing valley creating a cliff and, eventually, a waterfall. IT IS EROSIONAL
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Striations
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grooves carved into the bedrock. IT IS EROSIONAL
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Glacial Till
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sediments deposited directly from the glacial ice. VERY POORLY SORTED –contains ALL grain sizes including clay to boulder sized sediments.
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Outwash
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sediments deposited in glacial outwash streams. POORLY SORTED - contains all sediment sizes EXCEPT clay.
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Loess
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wind deposited, loosely consolidated silt particles deposited around the perimeter of a glacier.
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Discharge
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the total volume of water that passes any point in the stream in a certain amount of time
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Formula for Calculating Discharge
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Q=VA
Velocity (V) x Unit Area (A) = Discharge (Q) |
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Stream Competence
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the maximum size sediment that can be transported by a river via suspension in the water column, sliding, rolling or bouncing (saltation) along bottom
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Stream Capacity
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the maximum amount of sediment that can be transported by a river at a given time
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V-shaped valley
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In geology, a valley or dale is a depression that is longer than it is wide
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Floodplain
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an area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding
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Stream profile
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a view of a stream's course from its headwaters to its mouth, showing the steepness of the descent
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Stream channel
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a type of landform consisting of the outline of a path of relatively shallow and narrow body of fluid, most commonly the confine of a river, river delta or strait. Channels can be either natural or human-made
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Alluvium
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a deposit of clay, silt, sand, and gravel left by flowing streams in a river valley or delta, typically producing fertile soil
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Oxbow lake
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a curved lake formed at a former oxbow where the main stream of the river has cut across the narrow end and no longer flows around the loop of the bend
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River valley
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an elongated lowland between ranges of mountains, hills, or other uplands, often having a river or stream running along the bottom
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Meander
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a winding curve or bend of a river or road
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Cut bank
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also known as a river cliff or river-cut cliff; the outside bank of a water channel, which is continually undergoing erosion
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Point bar
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an alluvial deposit that forms by accretion on the inner side of an expanding loop of a river
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Delta
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a land form that is formed at the mouth of a river where the mainstream splits up into several distributaries
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Bird’s foot delta
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a delta (as that of the Mississippi river) having many levee-bordered channels extending seaward like outstretched claws
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Sinuosity
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the ratio between the overall length of the stream channel and its ideal, straight line path. It is essentially a measurement of the amount to which a stream meanders
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Clastic
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also called Detrital; a sedimentary rock made up of pieces of preexisting rocks
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Biogenic
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also called Organic; made up of shells or fossils, plant fragments, or carbon
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Chemical
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also called Inorganic; mineral crystals precipitated from aqueous solution
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Grain Sizes
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• Gravel –>2mm
• Sand – can see grains and feels very gritty • Silt – cannot see grains, but feels gritty • Clay – cannot see or feel grains |
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Grain Shapes
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• Angular: sharp corners
• Rounded: smoother corners but still irregular surfaces • Well-rounded: no corners – whole grain is round |
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Grain Sorting
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• Poorly sorted: grains of several different sizes
• Moderately sorted: grains of only two or three closely related sizes • Well-sorted: grains all about the same size |
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Parent Isotope
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the original, radioactive isotope in a sample
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Daughter Isotope
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the final, stable isotope in a sample
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Half-Life
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the time it takes for ½ of the parent isotope to decay to the daughter isotope
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Absolute age dating
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also called carbon dating (or C-14 dating)
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Limitations of absolute age dating
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• C-14 dating can only date ORGANIC material.
• C-14 can only be used to date material younger than 60,000 years old. • A clean or pristine sample is usually needed to get a good reading • It is expensive |
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The principle of fossil succession
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states that different species of fossils appear in a definite order. The lower layers of a rock formation contain the oldest species. After that, newer species are arranged consecutively.
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Original Horizontality
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sedimentary strata and lava flows are laid down horizontally. Any variation happened after they were initially deposited.
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Lateral Continuity
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strata and lava flows extend laterally in all directions until they pinch out or reach the edge of their depositional basins
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Superposition
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the oldest layer is at the bottom, younger layers on top
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Inclusions
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older than its surrounding matrix
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Cross Cutting
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anything that cuts across strata or flows must be younger than the bed. INCLUDES Fractures, faults, or igneous intrusions
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Unconformities
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represent a gap in the rock record. Either deposition stops OR sediment has been eroded away.
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Compression
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when rocks are crushed inward into themselves
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Tension
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When rocks are pulled apart
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Shear
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when rocks split and slide against themselves
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Syncline
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a fold in rocks in which the rock layers dip inward from both sides toward the axis.
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Anticline
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a fold with strata sloping downward on both sides from a common crest.
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Basin
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a large, bowl-shaped depression in the surface of the land or ocean floor
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Normal Fault
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The hanging wall has slipped down in comparison to the foot wall. Gravity causes the hanging wall to slip down. Normal Faults are from layers being pulled apart. Also known as a gravity fault.
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Transform Fault
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a special variety of strike-slip fault that accommodates relative horizontal slip between other tectonic elements, such as oceanic crustal plates. Often extend from oceanic ridges.
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Reverse Fault
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a type of fault the hanging wall has slipped up in comparison to the foot wall. When layers are pushed together this is the kind of fault that occurs. Also known as a thrust fault.
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Graben
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a usually elongated depression between geologic faults.
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Shock Metamorphism
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process by which rocks are altered in composition, texture, or internal structure by extreme heat, pressure, and the introduction of new chemical substances
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Contact Metamorphism
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the mineralogy and texture of a body of rock are changed by exposure to the pressure and extreme temperature associated with a body of intruding magma. Contact metamorphism often results in the formation of valuable minerals, such as garnet and emery, through the interaction of the hot magma with adjacent rock.
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Regional Metamorphism
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the mineralogy and texture of rocks are changed over a wide area by deep burial and heating associated with the large-scale forces of plate tectonics. In regional metamorphism, rocks that form closer to the margin of the tectonic plates, where the heat and pressure are greatest, often differ in their minerals and texture from those that form farther away
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Monocline
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this is a type of fold where the rock layer has a gently dipping bend in the horizontal rock layer.
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