PLANET EARTH FINAL REVIEW RIVERS Equilibrium Profile Natural profile a stream strives to achieve Base Level lowest point a stream bed can reach Base Level Changes Lower base level steeper profile increase of stream erosion down cut incise Raise base level shallower profile infill shallow areas deposit sediment Types of drainage patterns Dendritic looks like the veins of a maple leaf that flows over a uniform surface Radial flows from the centerpoint of a mountain or volcano downwards cutting paths Looks like wheel spokes Rectangular Controlled by grid of fractures as joints or faults specifically right angle joints Trellis forms in long valleys where the trunk stream cuts resistant ridges to form water gaps Forces at river bends Meandering streams Occurs at river bends when the outer bank erodes while sediment deposits build the inner bank Braided River Channel that consists of smaller separated channels Alluvial River Intermittent streams dump sediment after exiting mountain front Alluvial fan mouth of alluvial river where sediment is deposited Sediment Movement When flow velocity decreases sediment grain sizes are sorted by water Sediment Load o Dissolved load mineral ions dissolved in the water o Suspended load clay and silt sized particles floating in suspension o Bed load sand and pebbles pushed rolled along stream bed Deltas Alluvial fan in water forms from sediment deposits at the mouth of a river in the shape of a triangle Greek Delta OCEANS COASTS FIVE OCEANS Pacific Atlantic Indian Arctic Southern Origin of water outgassing steam from volcanoes and comets led to water vapor in the form of ice and dust Continental margin morphology Deep ocean trench convergent boundaries where lithospheric plates subduct into the mantle o Deepest parts of the ocean Passive continental margin trailing edge shelf is farther out with a gentle slope Active continental margin leading edge shelf is close to the coastline steep slope with an adjacent trench Continental shelf broad and flat from shoreline to the continental slope and is also underlain by continental crust o Shallow shelves are affected by waves and tidal currents Dominant sediments nearshore sand offshore silt mud o Carbonates occur where little land derived sediment input Continental Slope typically mud draped it marks the edge of a continental shelf which can extend 4km downward and create submarine canyons Continental rise gently sloping sediment apron that forms at the bottom of the continental slope where sands and muds deposit Creates large submarine fans Abyssal plain Beyond the continental rise in the deep sea It is the flattest surface on the earth and forms the largest part of the ocean Sometimes there are large submerged volcanoes called seamounts on the abyssal plain o Abyssal hills located on the side of mid ocean ridges where the abyssal plain meets the mid ocean ridge Ocean water evaporates precipitates onto land and the runoff collects more salts which increases the salinity of the ocean Salinity and temperature control ocean density Tide vertical movement of sea level due to o Gravitational pull of Moon Sun o Centrifugal force rotation about the center of mass between earth and moon Ocean salt Tides forces Currents Waves Surface currents controlled by the wind and the Coriolis effect earth spins faster at the equator Deep currents controlled by temperature and salinity density Wave Undulation in the sea surface usually the wind without disturbance the sea surface is usually smooth Wave height dependent on o Wind velocity how fast o Wind duration how long o Fetch distance over which wind blows how far Wave Motion o Circular no net horizontal translation o Circular motion decreases with depth Waves on the shore Wave height increases Wave length decreases Velocity decreases Wave refraction wave bends in non normal angle because of lower wave velocity due to shallow water Longshore Sediment is transported near the shore parallel to the beach Longshore current currents parallel with the beach within the surf zone Longshore drift sand movement by swash and backwash along the beach Beach Morphology created by waves Winter summer trends face Summertime beach produced by light wave activity wide sandy berm steep beach face Wintertime beach produced by high wave activity narrow and rocky berm flattened beach Bedrock coasts forms from waves crashing into exposed bedrock during high tide During low tide the berm is rocky Erosion manmade structures are built to prevent erosion although they cause localized erosion Groin manmade structure that stops longshore drifts and creates beaches o Longshore current creates erosion by moving sand to one side of the groin exposing the other side Breakwater manmade structure built behind the surf zone to prevent beach from washing away Jetty two parallel manmade structures used to protect beaches from longshore drift usually at an inlet or harbor entrance for boats to use Seawall no beach waves crash into a manmade wall GROUNDWATER Water Table surface of groundwater boundary between saturated and unsaturated zone Varies due to seasons evaporation precipitation and topography Perched Water Table Small area of groundwater that is in the unsaturated zone separated from the main water table Pore open space in a rock Porosity total volume of all pores as total rock volume Pores can contain water Primary Porosity Original porosity of a rock Secondary Porosity Secondary porosity system of a rock due to chemical leeching or fracturing Porosity Permeability The ease with which water flows through a rock Affected by o the number of available conduits channels o size of conduits o straightness of conduits HIGH POROSITY DOES NOT IMPLY HIGH PERMEABILITY Recharge where groundwater is replenished Recharge area area where precipitation reaches saturation zone Discharge where groundwater flows from the surface Discharge area where subsurface water is discharged to streams lakes ponds or swamps Aquifer Sediment rock through which water flows easily Aquitard Sediment rock that restricts the flow of water Artesian hydraulic gradient is large enough to cause groundwater to flow upwards and out of the ground Caves forms when water table sinks They will only form in carbonate material i e limestone or dolomite Karst landscape forms when underground cave collapses GLACIERS Till silty sandy matrix with poorly sorted rounded pebbles gravel and boulders MOVED BY ICE Snow accumulation function of annual solar