As a result of escalating racial tension at Dartmouth College, a moratorium on classes was declared at the Ivy League institution today, the first since the American incursion into Cambodia in 1970.

Undaunted by the frenzy of final examinations just three days away, hundreds of the nation's most competitive college students today jammed historic Daniel Webster Hall in "an experiment in communication," as President Hohn G. Kemeny termed it.

"There's been too much rhetoric, there's been too much intolerance, there have even been attempts at intimidation," Kemeny said.

"Things are getting really bad around here. It's getting scary," said Howard Kelly, a black senior who grew up in Harlem, far from the kind of placid rural academic atmosphere of Dartmouth College.

Some minority students, about 400 out of 3,500 undergraduate students here, said they have been threatened with phusical harm and damage to their living quarters because of a symbolic protest staged last Friday. Racial epithets yelled from passing cars, they said, are a matter of course.

"The situation has been building up for a long time," said Marsha McNair of the Afro-american Society. "Then several incidents happened at once."

Last spring, during "Sink Night," the wild installation ceremony for Dartmouth's notorious fraternities, on which the movie "Animal House" is based, one group hanged in a noose what appeared to be an effigy of a black man. It was called by the administration "an unfortunate individual act."

Recently, a full-page photograph of a black English professor, William Cook, was printed on the cover of the university alumni magazine. In what minorities point to as overt examples of racism, letters from alumni decrying the use of the photograph were published.

"Horrible, horrible," read a letter from Donald Wilbur, class of '24, of Wellesley Hills, Mass. Robert E. Cleary, class of '26, of Long Valley, N.J., wrote, "I am truly appalled at the lack of judgment shown in the selection of the cover... in the midst of the annual alumni fund campaign.... The timing could not be more damaging."

And then, in mid-February, while other fraternities were admiring the ice sculptures they had created for Winter Carnival Weekend, the school's only black fraternity was hit by what members said they thought was an act of cold hate.

They had built a graveyard, a monument to the black victims of South Africa, in a protest against Dartmouth's large investment in South African interests.

A campus maintenance worker dismantled the graveyard, he said, on orders to clean up the area. But, said Donald O'Bannon of the black fraternity, Alpha Bhi Alpha, "Any fool could have seen it was part of a sculpture. I can't believe he thought that was trash."

On Feb. 25, shortly after the Dartmouth hockey team entered the ice for the second-period play against Boston University, two students dressed as Indians skated onto the ice to the cheers of thousands of students as the band led the group in the Dartmouth "Scalp 'Em" fight song.

The school's more than 40 native Americans -- whose sensitivity over use of the Indian as an athletic symbol in an institution originally founded to educate Indians prompted its ban several years ago -- didn't think it was funny. The offending students were disciplined, but their sentences were suspended by Kemeny.

"It was the straw that broke the camel's back for minorities here," said Afro-American Society President James Defranz.

A list of demands was issued calling for expansion of black studies programs as well as 13 other points. Women called for vigorous recruitment of minority women and support for an expansion of a women's study program.

Last week, several hundred minority students and women marched on the centerpiece of the winter carnival -- an ice sculpture of a gold miner.

The sculpture was defaced and spray-painted black by blacks and red by native Americans. Women also chipped in.

"And then the calls started coming, threatening to trash the Afro-American Society," said Defranz. "We just huddled in Cutter Hall together that night."

The tension sparked a flurry of meetings between the administration and heads of fraternities in an effort to keep their members in line over the weekend.

And today, standing on the stage where Martin Luther King Jr., George C. Wallace and Robert Frost once spoke, Kemeny told the angry students, "I assure you that this college, through its faculty, administration and trustees, deeply cares about you." A meeting was set for April 9 to discuss the minority demands formally.