GEOL 101 1nd EditionExam # 3 Study Guide Lectures: 19-26Lecture 19 -The hydrologic cycle: summary of the circulation of Earth’s water supply; driven by energy fromSun and atmosphere is link between ocean and continents•Processes involved: Precipitation (condensed water molecules that fall from atmosphere), Evaporation (transfer of liquid water at surface to water vapor), Infiltration (movement of surface water in ground through rocks and soil), Runoff (water that flows over the surface with NO infiltration), and Transpiration (release of water vapor into air by plants).-Sheet flow: Thin, broad sheets of water flowing across the ground-Channel flow: Sheet flow develops into little channels called rills. Form larger channels -Infiltration capacity: how much water can seep into the ground•What affects it: intensity and duration of rain, how wet/dry soil was, soil texture, slope of land, and nature of vegetative cover. -Stream flow: Depends on velocity•Laminar: slow moving water moves in a relatively straight line •Turbulent: fast moving water is more erratic and can have whirlpools, eddies, and rapids-Factors determining stream flow: Gradient (steepness of stream), Channel characteristics (shape, size, roughness), and Discharge (volume of water moving past a given point in a period of time)-Stream profile – changes from headwaters to the mouth: view from head (source) to the mouth, profile is smooth curve, gradient decreases downstream. From head waters towards mouth  discharge increases, channel size increases, gradient is more gentle, and roughness decreases, -Work done by running water: erosion, transport, deposition: stream currents dislodge clay, silt,and sand from stream and carry them along current. Strong currents pick up large particles while weak ones pick up clay and silt-Types of stream loads (material being transported):•Dissolved: material that is a solution from chemical erosion of soluble rocks (limestone, marble, salt)•Suspended: silt and clay sized particles that are carried with the current •Bed: coarse particles (sand sized increase) more along bottom of channelLecture 20-Flood plains & features •Levees: form parallel to stream channel by successive floods over years•Yazoos: small streams that run parallel to main river between levee and valley wall•Back Swamps: marshy lands between levels and valley walls-Stream valleys: consists of stream channel and surrounding terrain•v-shaped: gradient is steeper at headwaters which causes valley deepening; downward erosion dominates and develops features like rapids and waterfalls•broad flood plains: towards mouth of river -Features of stream valleys•Ox-bows lakes: as stream meander, part of meander can be cut off from river and segments are called oxbow lakes•Cut Bank: outside meander, erosion is active•Point Bars: inside a meander, deposition is active•Terraces: remnants of former flood plain, river adjusted to relative drop in base-Drainage patterns: interconnected network of streams in an area•Dendritic: irregularly branching tributaries (most common)•Radial: streams diverge from center point (typical streams flow off of volcanoes)•Rectangular: streams bend at right angle (caused by fracture in bed rock perpendicular toeach other) -Floods: any event where the amount of water is too much for the channel to hold (most common and most destructive)•Regional: caused by long-duration precipitation (cover a large geographic area)•Flash floods: caused by intense short-duration precipitation (more localized areas) •Dam failure: man-made and natural dams may fail under any number of circumstances (too much water from previous floods or earthquakes)Lecture 21-Causes for variations in the water table:-Permeability: ability of a substance to transmit fluid-Gaining streams: streams gain water from inflow of groundwater through the streambed-Losing streams: streams lose water to the groundwater system by outflow through the streambed (may be disconnected by groundwater table)-Groundwater movement & Darcy’s law – know what variables are involved-Porosity: percentage of void or pore space in a rock body-types of porosities and associated rock types•Intergranular: due to space between grains (sandstones, claystone, conglomerates)•Bedding plane: due to space between the bedding of rock layers (sedimentary rocks)•Solution (vuggy): due to cavities within rocks that have dissolved from mild acids (limestone, marble, rock salt, gypsum)-Aquifer: permeable rock strata or sediment that transmit groundwater freely (rock types that commonly act as aquifers are medium-coarse grained sandstone and gravels)-Aquitard: impermeable layer that hinders or prevents water movement (shale and crystalline that are igneous or metamorphic are good because water can’t flow easily)-Groundwater pollution: Sewage (most common), fertilizers, pesticides, industrial materials, chemicals, landfills:-Caves: how are they formed? Groundwater that dissolves soluble rock below the surface. Caves have delicate balance of solution and dissolution and are called “living caves” and continuously making new cave formationsWhat rock type? Composed of dripstone (travertine)Lecture 22-Karst topography: dissolved limestone that is very close to the surface results in landscape features-Formation of features in karst topography:•Sinkholes: caverns that form close to the surface and roof may become unstable and collapse (areas have irregular terrain and sinkholes are major sources of water quality issues)•Natural bridges: remnants of a cave passage; forms when sink holes collapse on two sides•Karst towers: last remnants of massive limestone layers that form enormous “towers” (form in tropical regions)-Hot springs: water is 11-16 degrees F warmer than average annual air temperature of the locality. Heated by cooling of igneous rocks below. 95% located near volcanoes that are active-Geysers: intermittent hot springs where water erupts with great force (100-200 feet high)How do geysers work? Extensive underground chambers collect water which is heated by hot igneous rock below. (Groundwater eats, expands, and changes to steam and erupts)-Thermophiles: Yellowstone; organisms that can survive and thrive in extreme heat environmentsLecture 23-Types of glaciers: thick mass of ice that originates on land from accumulation, compaction, andrecrystallization of snow, capable of flawing under its own weight.