Jul 18, 2012 10:17 AM

The rate of erosion seemed to speed up sometime in the early 1990s, Mr. Warner said, surmising that a famous series of winter storms in 1992 and 1993 may have shifted channels and sandbars in Shinnecock Bay, redirecting currents or opening the shoreline to more wave action that magnified erosive effects.

“This is not that dissimilar to what happened at the North Sea Beach Colony,” Trustee Fred Havemeyer said, another site of erosion. “There’s no question that as time goes on there are going to be more and more of these hot spots.”

Mr. Warner agreed: “I think, eventually, the whole bay shore will look like this,” he said, gesturing to the bay’s northern shoreline, while standing atop one stretch of bulkhead where the water runs up to the foot of the wood wall.

The question is whether anything can be done to address the problem so that beaches and the access to the shoreline they afford—the Trustees’ primary interest in the stretch of beach—can be restored in some form.

As the entourage rounded Cormorant Point, walking to the south, they came upon a stretch of shoreline where sand once again rose up from the waterline to the bulkhead, and appeared to be enough to be dry even at an average high tide.

Mr. Warner pointed to where a dock and wooden ramp—built so a bulldozer could access the beach to work on the bulkhead of one house—bookended the stretch of shoreline, dampening the erosive effects of waves sweeping along the shoreline.

He also pointed out several wooden stumps, arranged in two parallel rows, protruding from the sand. The stumps, like the rotting dock piles seen earlier, were the remnants of rows of pilings buried in the beach that were stuffed with tree trimmings and brush, in order to capture sand and slow the erosion of the beach. These are the aforementioned brush jetties, which acted much like stone groins along ocean beaches do, capturing and holding sand between them. Until the 1970s, the brush jetties were maintained informally by local residents.

Such efforts, though effective, were outlawed as the state and local agencies began trying to halt the practice, since capturing sand from the natural flow can have harmful erosive effects down drift of the structures.

“It’s a good history lesson: Look what preserved the beaches for 60 years—brush jetties,” Mr. Warner said. “They kept the beaches somewhat stable.”