It was an elegant poolside luncheon to introduce a distinguished group of Washington friends to what sounded like a promising new role for a historic waterfront farm in southern Maryland.

But by today, local residents were circulating a petition protesting a dockside facility that may be key to plans that would make Point Farm, overlooking the Patuxent River and St. Leonard's Creek in rural Calvert County, a scientific center for marine studies.

The petition contends that to build such a facility would be "a flagrant breach of faith" because residents and property owners had been assured that all water access would be on the Patuxent at an existing dock rather than on neighboring Mackall Cove.

Point Farm was given to the State of Maryland two years ago today by Mary Marvin Breckinridge Patterson, 79, widow of Jefferson Patterson, a former ambassador to Uruguay and longtime foreign service officer as well as heir to the National Cash Register Corp. fortune. Mary Patterson is also the granddaughter of B.F. Goodrich, the tire tycoon.

She gave the farm to the state after she was assured that the property would become a park and museum. In turn, she has been granted use of her house and 15 acres for her lifetime.

With the park in operation for a year, Wayne E. Clark, director of Jefferson Patterson Park and Museum, spelled out development plans for what has been called a Woods Hole for Chesapeake Bay. Woods Hole is a world-famous scientific complex for marine studies at the base of Cape Cod.

According to Clark, Point Farm will also be the site of a new $3.5 million facility for marine studies. Scientific partners in the center are the Calvert Marine Museum, the Chesapeake Biological Laboratory of the University of Maryland, and the Estuarine Research Laboratory of the Academy of Natural Sciences in Philadelphia.

Reports that picturesque Mackall Cove bordering the site would become port for research vessels has angered many St. Leonard's Creek residents accustomed to waterscape views marred only by sunsets and the graceful sails of yachts.

Details of any such plan were not immediately available from Clark, who could not be reached today, but John M. Gott Sr., chairman of the Calvert County Commission, confirmed plans for a docking facility but said it was his understanding that "only runabout boats" would be used.

The Maryland Historical Trust is scheduled to sign a lease with the Solomon's Environmental and Archeological Research Consortium June 27.

The object of a petition being circulated up and down St. Leonard's Creek is to stop that agreement from being signed. Pat Meagher, who lives at Morgan Hill Farm, a colonial house overlooking the creek, said she and other residents had been assured no such docking facility or any other development would occur at Mackall Cove. This was a year ago when state officials, including Clark, informally met with residents of St. Leonard's Creek.

Chesapeake Bay yachtsmen count Mackall Cove among the most picturesque anchorages in the entire region. It was that part of that view that captured the eye of Patterson's guests Saturday at the luncheon she gave in honor of former Smithsonian secretary S. Dillon Ripley. Following the luncheon, guests were given a bus tour of the park's early colonial archeological excavations and in a slide show were told about plans for the new marine studies center.

Guests were unable to visit Mackall Cove, which was reachable only by private property, but some, like Justice Sandra Day O'Connor and West German Ambassador Gunther Van Well, did explore the nearby view from Peterson Point on the Patterson property.

Earlier many of Patterson's guests had delighted in getting their hands dirty all in the interest of history and science.

Setting what may be a new standard in Washington area party-going, O'Connor, Van Well and several other ambassadors eagerly crumbled lumps of dirt between their fingers from archeological digs all around them, hoping to find artifacts from a bygone age.

They and 40 others took turns standing at waist-high screening tables where volunteers have been helping Maryland archeologists excavate the site of a 17th-century plantation, known as King's Reach, on what some experts believe is one of the richest natural preserves of its kind.

In addition to the plantation site, 512-acre Jefferson Patterson Park and Museum offers 12 million fossil deposits from the Miocene period; sites of Indian occupation dating back 12,000 years; evidence that the colonial port of St. Leonard was once there; the setting of Maryland's largest naval battle in the War of 1812; and farmland still under active cultivation.

"If I had to preserve a part of Maryland that contains a sample of everything, I couldn't have picked a better spot geographically, architecturally, archeologically and historically," said Clark of the park, which traces 2.5 miles of coastline along the Patuxent River and St. Leonard's Creek.

Moving among the screening tables was the benefactor of it all, photographer, war correspondent, foreign service wife and philanthropist Patterson, smartly attired in red Italian-designer knickers. Among the guests she chatted with were Turkish Ambassador Sukru Elekdag, Kennedy Center Chairman Roger L. Stevens, U.S. Ambassador (recently returned from Venezuela) George W. Landau, Virginia Museum of Fine Arts Director Paul N. Perrot and Maryland Comptroller Louis Goldstein. Also present was Calvert County Commission Chairman Gott.

Clark, who called Point Farm the "largest gift of its kind ever given to Maryland," expects the number of archeological sites to hit 100 before excavations have been completed. Two Calvert County residents who played key roles in persuading the state to accept Patterson's gift were Goldstein and Gott.

"Goldstein was pivotal in the negotiations and when deed discussions were under way, he was in there the whole time," said Clark.

Coincident with the luncheon for Ripley was the invitation to Patterson's guests to join a newly organized support group called the Friends of Jefferson Patterson Park and Museum, with Goldstein as honorary chairman.