GEO 121 10th Edition Final Exam Study Guide Lectures 34 39 Lecture 34 April 29 A Forms of Mass Wasting i Creep slow downslope movement of Earth material involving the lifting and falling action of sediment particles ii Earthflowiii Landslide Layperson s term for any fast mass wasting used by some earth scientists fir massive slides that involve a variety of earth materials iv Slump Thick unit of unconsolidated fine grained material sliding downslope on a concave curved slip plane i Streams i Perennial Describes streams that conduct flow continuously all year ii Intermittent Describes streams that conduct flow seasonally ii Stream Patterns i Dendritic A term used to describe a drainage patterns that is treelike with tributaries joining the main stream at acute angles ii Trellis Develops in folded topography like that found in the Appalachian Mountains of North America Down turned folds called synclines form valleys in which resides the main channel of the stream Short tributary streams enter the main channel at sharp angles as they run down sides of parallel ridges called anticlines Tributaries join the main stream at nearly right angles iii Radial develops around a central elevated point This pattern is common to such conically shaped features as volcanoes The tributary streams extend the head ward reaches upslope toward the top of the volcano ii Cycle of Erosion i Young In this stage the river flows along an uneven surface and there is intensive bottom erosion the gradients are steep and the erosion is rapid The rapid deepening of the channel leads to the formation of V shaped valleys ii Mature In this stage rivers flow with a graded profile i e it attains a profile of equilibrium The land mass is fully dissected and a well integrated drainage system is developed Ridges and valleys develop prominently Flood plains develop and river meandering takes place The topography consists of features such as hogbacks cuestas mesa butte meanders oxbow lakes natural bridge flood plains alluvial fans etc iii Old Age In this stage the gradients are gentle and the velocity is low Accordingly the river lose most of its erosive power and flow in a sluggish manner In old age a river has maximum meandering The river at this age does little of erosion and transportation but is mostly engaged in deposition This stage is characterized by the development of distributaries and the river flows almost at the base level of erosion The topography consists of features like peneplains natural levees deltas etc iv Additional Notes Most of the cycles of erosion do not reach the final stage as sometime during their operation either climatic or tectonic disturbances take place and thus results in an incomplete or partial cycle Lecture 35 May 1 A Fluvial Processes a Erosion Removal of Earth materials from a site by gravity water wind or glacial ice b Transportation Movement of Earth materials from one site to another by gravity wind water or glacial ice c Deposition Accumulation of Earth materials at a new site after being moved by gravity water wind or glacial ice B Fluvial Landforms a Back Swamps In geology backswamp is the section of a floodplain where deposits of fine silts and clays settle after a flood Backswamps usually lie behind a stream s natural levees b Flood Plains A low gradient area adjacent to many stream channels that is subject to flooding and primarily composed of alluvium c Valley An elongated lowland between ranges of mountains hills or other uplands often having a river or stream running along the bottom d Bluff A bluff is a steep cliff or wall of rock or soil Most bluffs border a river or its flood plain Bluffs may form along a river where it meanders or curves from side to side Water on the outside of the curve flows faster This erodes or wears away the lower part of a river bank No longer supported the upper part of the bank breaks off leaving a high steep wall e Meander A broad sweeping bend in a river or stream f Meander Scars A meander scar occasionally meander scarp is a geological feature formed by the remnants of a meandering water channel They are characterized by a crescentic cut in a bluff or valley wall produced by a meandering stream They are often formed during the creation of oxbow lakes g Ox bows Lakes or ponds that are found in the meander cut off on a flood plain h Cut Bank The steep slope found on the outside of a bend in a meandering stream channel i Point Bar Deposits Deposit of alluvium found on the inside of a bend in a meandering stream channel j Natural Levees A bank of a stream channel or margin of mass wasting flow channel raised by deposition from flood or flow deposits artificial levees are sometimes built along stream banks for flood control Lecture 36 May 4 A Ground Water a Infiltration The process of water seeping downward into the soil or other surface materials b Percolation Subsurface water moving downward into the lower zones by the pull of gravity c Zone of Saturation Subsurface water zone n which all voids in rock and soil are always filled with water the top of this zone is the water table d Water Table Upper limit of the zone of saturation below which all pore spaces are filled with water e Aquifer A rock layer that is a container and transmitter of groundwater it is both porous and permeable f Cone of Depression A cone of depression occurs in an aquifer when groundwater is pumped from a well In an unconfined aquifer water table this is an actual depression of the water levels In confined aquifers artesian the cone of depression is a reduction in the pressure head surrounding the pumped well B Ground Water Related Landforms Karst a Caves Also called a cavern a natural void in rock created by solution that is large enough for people tom enter b Sinking Streams Any stream that disappears underground typically into a swallow hole c Sinkholes Also called a dot line a roughly circular service depression related to the solution of rock in Karst areas d Karst Unique landforms and landscapes derived by the solution of soluble rocks particularly limestone B Glacial Processes a Snow Precipitation in the form of ice crystals b Firn Compact granular snow formed by partial melting and refreezing due to overlying layers of snow c Glacier A large mass of ice that flows as a plastic solid Lecture 37 May 6 A Ages a Pleistocene The interval of Earth history immediately before the present Holocene epoch that experienced times of glacial advance and lasted from about 2