Three years to the day after Richard Nixon resigned from the presidency, the last and most sensitive of his White House tapes and papers were moved to new quarters.

Shortly after 7 a.m. yesterday, workmen began loading three large trucks with the materials for the move from the old Executive Office Building to the General Services Administration's National Archieves building on Pennsylvania Avenue and 8th ST. N.W. Secret Service officers and two armed forces patrol cars guarded the trucks during the move.

The materials include the celebrated Watergate tape recordings - some 1.140 of them - and 1,800 boxes of papers , about 3.6 million pages.

These papers include National Security Council files, Nixon's personal papers and those of his senior aides, H.R. Haldmen, John Ehrlichman, John Dean, Charles Colson and Alexander Haig.

On June 28 the Supreme Court upheld, 7 to 2, the 1974 Presidential Recordings and Materials Preservation Act, which directed the government - not, Nixon - to decide what was private and what should be accessible to the public. Because of his unusual departure from office, Nixon became the first President in American history unable to exert control over his own papers. Yesterday's move was in accordance with the court decision.

In May 1976, GSA got most of Nixon's presidential materials, about 25,000 cubic feet of paper, or about 50 million pages. These are stored in GSA's record center in Suitland, Md. The new materials will be stored inside vault "buried inside" the National Archives building, said Richard A. Jacons, and archivist for presidential libraries. But scholars who want to look at them will have to wait.

"Processing these materials," said GSA Administrator Jay Solomon, in announcing the move yesterday, "will take a minimum of three years. It will be at least a year before the first portions become available to public researchers.

Jacobs said it could take longer than that. Assuming Congress approves GSA's regulations for processing the material, he said, Nixon or anyone else could litigate the constitutionality of the regulations, and that could take a few more years. He said he hopes the Supreme Court will allow archivists - GSA wants 103 for the project - to at least process the material before the question is settled. He said the papers should be examined for "physical deterioration" and the tapes rewound rerecorded to assure preservation.