Six thousand years ago, according to native legend and scientific calculation, Nantucket Sound was dry land, and people probably lived and hunted and fished there. Until global warming caused the sea to rise and cover the place.

Ironically, the fact of that long-ago drowning now has become the basis of the latest challenge to the Cape Wind proposal to build a wind farm in Nantucket Sound. The big selling point of Cape Wind is that it would generate power without contributing to global warming, sea level rise and coastal flooding.

But that is at the root of the finding last week by the Massachusetts Historic Preservation Officer Brona Simon, supporting a claim by the Wampanoag tribes of Mashpee and Aquinnah that Nantucket Sound should be included on the National Register of Historic places as a traditional cultural property.

“Prior to 6,000 years ago, Nantucket Sound was exposed land,” she wrote in the opinion.

“Native groups would have occupied the exposed lands, and focused their gathering and hunting and social activities near fresh water and estuarine settings that are now submerged under the waters of Nantucket Sound.

“The Pleistocene-Holocene geology of Nantucket Sound shows the area ice-free by about 18,000 calendar years ago, containing favorable environmental settings in transformation that provided abundant resources and opportunities for Paleoindian exploration and occupation.”

Evidence of that ancient occupation of the land probably still exists on Horseshoe Shoal under 50-odd feet of Atlantic Ocean, Ms. Simon said.

Elsewhere in the New England region, she noted, extinct Pleistocene fauna and artifacts dating to the Archaic period had been turned up by scallopers dragging the seabed. And core samples taken by the Cape Wind proponents “detected submerged, ancient terrestrial soils with preserved wood, charcoal, plants, and seeds in intact contexts that survived the submergence of Nantucket Sound.”

The samples could be interpreted as evidence of “precisely the kinds of ancient landforms and environmental settings where ancient Native American features and artifacts are expected to be found in Nantucket Sound.

“Submerged sites have the potential to yield whole categories of ancient material culture that are usually absent from terrestrial sites.”

Ms. Simon was not just talking about archeology, but rather about living tradition which carried on from those ancient times.

The oral tradition of the Aquinnah Wampanoags referred to their ancestors having walked to Noepe, the Algonquin word for Martha’s Vineyard. Their stories recorded how the giant Maushop discovered the Vineyard and created the Elizabeth islands and Nantucket, transformed his children into whales and flung dead or dying whales ashore to feed his people.

To this day, Ms. Simon said, the Wampanoags maintain a close spiritual and practical relationship with the waters of Nantucket Sound by fishing and guiding tourists on boats and engaging in enterprises like shellfish hatcheries.

“The very meaning of ‘Wampanoag’ rendered in English as the phrase ‘People of the First Light or Dawn’ refers to their relationship to Nantucket Sound . . . is both temporally literal — they have always been/are/will be the first people to see the sunrise over the water — and symbolically referential: they are of the place, it is how they identify themselves and how others know them,” she wrote.

Her finding that Nantucket Sound meets all criteria for listing it as a traditional cultural property means that the matter now goes to the National Parks Service and ultimately to Secretary of the Interior Ken Salazar for a ruling.

It also means more delay for the Cape Wind project, which has been in the works for more than six years and has cleared state and federal hurdles at every level — until now.

Cape and Islands Rep. Tim Madden said this week that he believes the ruling will not be fatal to Cape Wind.

“I just think it is going to go forward and it’s going to be done. This won’t stop it,” Mr. Madden said.

Mr. Salazar is being pushed to decide against the Wampanoags’ claim by a large number of powerful voices.

On Monday Massachusetts Cong. Ed Markey, who is chairman of the Select Committee on Energy Independence and Global Warming, wrote to Mr. Salazar, calling for him to move quickly to issue the final federal permit for Cape Wind, as an indication of America’s intent to get serious about climate change, ahead of the United Nations Climate Change Conference which begins in Copenhagen on Dec. 7.

In an editorial last week before the release of Ms. Simon’s opinion, The New York Times called the tribes’ position “unsupportable.”

Others who have pushed Mr. Salazar to overrule Ms. Simon and the Wampanoags’ claim are Ian Bowles, the state Secretary of Energy and Environmental Affairs, who wrote on July 15 saying the designation of 560 square miles of ocean would cause “severe unintended consequences and create unnecessary and duplicative regulatory burdens.”