Coastal Processes ~ erosion, transport & deposition 12.1 CA NC Erosion http://geobytesgcse.blogspot.com/2007/08/coastal-processes-erosion-transport-and.html Erosional processes • Abrasion = continuous tumbling reduces rock to sand grains • Solution = salt dissolves some of the rock • Scouring = wave swirls at base of cliff & loosens rock Erosion • Erosional processes in action • http://www.bbc.co.uk/schools/gcsebitesize/ge ography/coastal/coastalprocessesrev3.shtml Erosional Features • • • • • Sea cliff Sea cave Sea arch Sea stack Terrace Sea cliff Navassa Island, Caribbean Sea • Forms when waves erode rock http://coastal.er.usgs.gov/navassa/photos/ep/hike/CliffE.jpg Sea cave Short Sands Beach, Oregon • Hole eroded at base of cliff http://web.cecs.pdx.edu/~walpole/pics/kayak/falcon/cave3.jpg Sea arch Hawaii • Sea cuts through headland http://upload.wikimedia.org/wikipedia/commons/e/eb/SeaArchHawaii.jpg Sea stack County Mayo, Ireland Isolated column of rock http://ts1.mm.bing.net/images/thumbnail.aspx?q=1023555809064&i d=45685568345e0ba48cec1d6807ea14ba&url=http%3a%2f%2fwww.v isualphotos.com%2fphoto%2f2x4004071%2fdoonbristy_sea_stack_do wnpatrick_head_ballycastle_1813001.jpg Sea terraces Haiti • Flat platforms at water height http://www.amishkin.com/wp-content/uploads/2010/03/P1000346-Large.jpg Features Transport • Material eroded by the sea is moved along the beaches. Longshore drift • Longshore drift illustration • http://www.bbc.co.uk/schools/gcsebitesize/ge ography/coastal/coastalprocessesrev4.shtml • Waves approach beach at angle • Sand moves in zig zag motion • Creates longshore current • Current keeps sand moving until it hits a change or structure, then it drops out. Longshore drift diagram http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchamb ers/GeoBytes%20GCSE%20Blog%20Resources/Images/Coasts/Longsho re_Drift.jpg Deposition • Sand deposits form where amount of rock moving toward shore is greater than amount moving away. Depositional Features • • • • Beach Lagoon Tombolo Barrier island Beach Emerald Isle, NC http://www.tripadvisor.com/LocationPhotos-g49113-Emerald_Isle_North_Carolina.html Lagoon Vegetation is red; water is blue (satellite image) Tombolo Bar that extends out into ocean, but remains connected to mainland. web.macam.ac.il web.macam.ac.il Barrier Island http://www.frf.usace.army.mil/outerbanksaerialfligh t/Index.htm Barrier Islands • • • • Occur on east coast of USA Isolated dunes become islands Parallel to shore Associated features: – Sound (also called bay or lagoon) – Tidal inlets – Tidal flats – Estuaries HUMAN EFFECTS ON COASTLINES Homework • Read pages 342 - 347 Output • Draw a block diagram of the east coast and include the features of the beaches. • Draw a block diagram of the west coast and include the features of the beaches.