Tons of sand, pebbles, and other material get moved up and down the beach each year. This transport is called littoral drift.

The two most powerful influences on this drift along the Delaware and Jersey coasts are nor'easters and the sea breeze, and each has its own season. In summer, the sea breeze dominates with southeast winds, so waves tend to approach the beach from that direction. This creates a subtle movement of water and sand to the north. In winter, nor'easters cause much of the littoral drift. Their not-so-subtle northeast winds and pounding waves move sand in the opposite direction, to the south.

On average, the sea-breeze effect wins out along the Delaware Coast, so the overall drift of sand is to the north. The tip of South Jersey is partly responsible, because it helps to shield the Delaware coast from the pounding of nor'easters. But the farther south you go, the less the shielding. By the time you get to Fenwick Island, the drift to the north due to sea breezes and the drift to the south due to nor'easters approximately balance each other out.

Interestingly, south of Fenwick, the influence of nor'easters beats out the sea-breeze effect, so the overall drift there is south, helping to ever-so-slowly build the beaches of Ocean City, Maryland.