English: Shingle ridges on Orfordness The lines of the ridges are picked out by the vegetation pattern. Each ridge is from a past position of the coastline. The shingle is sorted as it is deposited with the smallest shingle at the top of the ridges and the largest stones at the bottom (swales). The smaller stones catch and hold organic matter and seeds more efficiently than the larger stones so the vegetation has developed along the ridges but not along the swales. Looking towards the Lagoon. The orientation of the ridges varies in different parts of the spit, with discontinuities indicating the limits of past erosional periods that have then been followed by depositional periods with a slightly different angle of coastline. From the viewpoint on the top of the old bomb ballistics building, which has interpretation boards about the studies carried out into bomb trajectories at Orfordness.