use the links below to help you with your HW on spits. The first one is a video feed-in from Miss Pritchard:-
https://www.youtube.com/watch?v=p1DFFgnWs88
http://blip.tv/geogtv/formation-of-spits-and-marshes-469845
http://geobytesgcse.blogspot.co.uk/2007/08/coastal-deposition-landforms-features.html
http://www.bbc.co.uk/schools/gcsebitesize/geography/coasts/depositional_landforms_rev2.shtml
