GEOG 2051 Notes on Coastal Processes PDF

- Wave curves over the peak in order to make a circle Wave refraction - The bending of the wave crest as a reaction of parts moving differently - Wave fragments move in different directions 1. (A) Longshore currents - Run parallel to a shoreline - Beach drift is a sediment...

- Wave curves over the peak in order to make a circle Wave refraction - The bending of the wave crest as a reaction of parts moving differently - Wave fragments move in different directions 1. (A) Longshore currents - Run parallel to a shoreline - Beach drift is a sediment that gets carried, groins showcase this Tsunami - The highest is small when first generated but the length is long - Water level tends to move offshore aka the trough Different types of coast 1. Sandy coast 2. Rocky coast - Bolder beaches - Cliffs 3. Muddy coast - Silt to clay - Tidal flats Primary vs. Secondary Primary - Owe much of the characteristics to terrestrial processes - Have not be modified by marine processes yet - Ria is a prime example: a stream erosion - Delta: owe the development to input sediment processes - Fiord: long narrow inland, very deep, a drowned river valley Secondary - Significant imprints from marine processes - Example wave-cut cliffs: wave attacks the cliff and start carving away the cliff - Barrier islands: formed by marine processes - Reef coasts: a main form of change by marine processes Erosional landforms - Set of coastal terraces - Wave cut platforms, until the overlying material is cut down - The relative space of the underlying material and the cliff, when sea level starts to fall - Forms a new wave cut platform at a lower level, creating the terraces 1. Arches - Waves carve completely into the headland and form a hole 2. Stacks - Nobs of rock near the shoreline that was at first an arch but then collapsed forming a stack Depositional landforms - Landscape landforms that are created by sediments being deposited 1. Beach cycle - Deposit of sediment that gets deposited on the shoreline - Fairweather “swell” waves: have low steepness, net transport on sediment is onshore - Wide beach, steep foreshore - Storm waves: short wavelength, but are steep having lots of energy, net offshore transport, erosion - Nearshore bar, leads to a narrower beach and a flatter foreshore 2. Spits - A long linear ridge of sediment that are created by longshore transport - As time passage it will get longer, since deposits are having as each wave comes 3. Tombolos - A ridge of sand, that runs perpendicular to the shoreline - Wave runs in the longshore current but a blocker stops it 4. Barrier islands - Long, narrow, islands of sand that run parallel to the mainland but are separated from them - Water in between is only a few feet deep - Ocean side and the bay or lagoon side based on vegetation - Foredune, a continuous ridge that's covered but intense vegetation - Can be stable, positive sediment budget (wider beach), negative sediment budget (shoreline retreat and erosion) 5. Barrier island rollover - A landward migration of an island in response to sea level rise - Underneath the salt marsh is peat soil, carbon rich  -Foredune has dune scarping -Plants will start to pop up and create a new fordune, however the placement of that dune will began near the salt marsh 6. Overwash fan - Water rushes across the island and there’s no push back so the sand stays there How did Barrier Islands form? 1. Drown in Place - Low sea level period and a foredune ridge and a gentle sloping coastal land 2. Spit extension - Barrier islands begin as a spit - Overtime the spit grows longer and longer then a breach occurs - A chuck of the spit turns into a barrier island Biological landforms - Coral reefs - Slow growing features - Thousands of corals that built up on top of former generations - Filter feeders - Biological conditions form where the coral reefs can go - They tend to form in only tropical and warm water Gyre - Northern hemisphere they flow clockwise - Southern hemisphere they flow counter clockwise - As they flow toward the Caribbean the water tends to get warm Preference to water toward coast line - Hugs the coastal since the algae needs sunlight to do photosynthesis - Tend to stay in shallow water with an area having lots of sun - Rivers dump huge amounts of sediment into the water so it’s never near a river Coral reef development stages - Near a volcanic island 1. Fringing reef - Coral reef hugs the island - As the hot spot moves the reef will start to grow vertically 2. Barrier reef - As the island is submerging the reef will continue to grow 3. Atoll Human impacts - Too many developments in the coastal zone 1. Sea level rise - Continue to rise in faster rates as the future progresses - Erosion is main impact from this - Literal zone tries to adjust to the sea level causing an uprise; shoreline retreat - Negative sediment budget causes erosion, positive budget adds sediments creating a new shoreline Solutions 1. Hard protection - Walls are oriented perpendicular to the waves called groins - Used to interrupt longshore current and dump the sand but causes a worse erosion problem on the other side - Breakwaters another approach - Small walls that are built by a nearshore zone, when waves come sediment accumulates by the wall - Jetties lock an inland in place - Stable shoreline - Destroys the existing ecosystem - Rocks replace the beach 2. Soft protection - Mimick’s natural processes - Beach nourishment continuously for years - Dune restoration, planting vegetation 3. Retreat The Cryosphere Cryosphere - Greenland ice cap, Arctic Ocean sea ice, and permafrost - Unique in its geography is controlled by the climate Earth’s energy budget - Temperature is the kinetic molecular energy that stored in a particle - Temp = stored energy - Any given object has a energy budget  - Positive budget = increase temp, negative budget = decrease temp - Greenhouse gases allows for the input of energy but does not allow for a release of that energy - Negative budget occurs from greenhouse gases Energy inputs - Spherical shape of the Earth and proximity to the sun - Rays the sun emits follows parallel paths - Curvature of the Earth allows for a larger spread of energy north and south Energy budget - Outputs of energy from the Earth goes latitude - Receiving more energy than were giving off Climate history - 15 C is the current global temperature - 2 billion years ago the temperature was so low it formed glaciers - Milankovitch cycles: three characteristics about the earth’s orbit around the sun 1. Eccentricity: shape of the Earth’s orbit, distance between Earth and sun changes 2. Obliquity: axis of rotation is not straight up and down its tilted; daylight savings time 3. Precession: the direction that the Earth’s point of axis is, shifts timing of which season occurs - Combined they effect glacial and interglacial periods Glaciers Distribution - Only 10% makes up the world today - Mostly down in Antartica Formation - Snowline: elevation that snow can remain throughout the year - Troposphere temperature profile - The weight of the underlying material gets crushed together called fern - Melt the fern together to form glacial ice Mass balance - Input is coming in the form of new snow, output is melted ice - Accumulation zone, ice is forming packing on top of another - Ablation zone, loss of snow at the bottom of the mountain - Advancing glacier; corresponds with a positive budget (+ VE) - Retreating glacier ( - VE)  - Stagnant (balance) Movement - Ice in the brittle (upper) zone, the ice tries to bend over the glacier - Plastic zone, bends and stretches; internal deformation - Glacial slip (basal): slipping along the ground - Glacial surge - Slow moment except during glacial surge Erosion - Plucking (melt and refreeze) 1. Occurs when the ice flows over an obstruction 2. The ice at the basis is getting squeezed causing melting of the ice up flow 3. Down flow, fingers of ice form from the cracks in the rock - Abrasion 1. Chuck of rock act like grains on a piece of sandpaper 2. Leave long tracks or grooves Alpine landforms (a) Preglacial - Tend to be broad and gently rounded - Deeply incised river valleys from water erosion (b) glacial - Ice is starting to melt - Covers majority of the valleys and land carvings - Glacial erratic: large boulders that are out of place (c) post glacial - Cirques round downwards - Downflow edge of the surface - Paternoster lakes also known as tarns - Tarns are round lakes in the middle of a glacial mountain - Aretes are sharp distinct ridges that separate cirques - Horn is the top of a mountain peak Glacial drift (Sediments) 1. Till - Large range of grain sizes - Sediment that had been laid down directly by the ice as it melts 2. Stratified Drift - Sorted into layers of different grain sizes  - Laid by melt water, it has been carried by running water that sorts the sediment Moraines 1. Terminal - The farthest point that a glacier reached 2. Recessional - The point in time where the glacier was stable as it was receding 3. Lateral - Sides of the glacier runs like a track - Ridge of sediment running along the side of the moraine 4. Medial - When the side and middle of the glacier meet together forming ridges Glacial Erratics - Pieces of rock that gets carried away from the source area - Out of place from surrounding area Continental landforms - Forms on a continent so doesn’t form from river valleys but flows in every direction - Till is a layer when the glacier is retreating 1. Esker - On the till layer - A bed of a former river 2. Kames - A filling of a hole that forms a inside out hill 3. Kettles - Form from dead ice that melt into the land - Leaves an empty space to form a kettle - Kettle lake is if it has water occupying the hole Two types of streamline hills 1. Drumlins - Depositional features that are created by sediment that leaves a deposit - Sculpted by deposits of sediment 2. Roche Moutonee - Hills that are covered by rock - Erosional features Periglacial Environments 1. Permafrost - Active layer: melt out 6 or 7 weeks in the spring season - Continuous/discontinuous: active layer of permafrost gets thinner and thinner/ thicker active layer but thinner permafrost - Water bodies keep the underlying ground from freezing - Talik: areas of unfrozen ground in an area of continuous permafrost 2. Frost action - Dock field: covered by layers of rock in extensive areas 3. Ice Wedge - A small crack in the permafrost - As the water melts it goes into the crack - Small crack produces large wedges of ice - Patterned ground: polygon shaped rock formed at the top of ice wedges 4. Cryoturbation - Can also produce patterned ground - Everytime the ground freezes the material gets brought up to the surface - Can form stone polygons 5. Pingos - Ice cord hills - Top of the pingos will collapse into the hole left by the ice 6. Drunken forest - Trees lose a lot of the underlying support cause the soil turns muddy - Have trees moving in every direction - Muskeg a very muddy material Human Adaptations - foundations & utilidors - Above ground tubes that help to keep them thawed out in the winter 1. Roads - Corduroy roads: log created roads to get around a muddy area - Ice roads: frozen enough that cars can safely drive on