This is a time lapse from Google earth engine that shows long shore drift of sediment at the bottom of cape cod. Due to the long shore current and lack of support structures the sediment is carried down the beach. This leads to erosion of the coast and creation and growth of spits.
https://earthengine.google.com/timelapse/#v=41.62334,-70.03734,10.167,latLng&t=3.23