Indians, environmentalists and others are alarmed by a proposal to extend a six-lane highway through the Petroglyph National Monument, an austere expanse of black volcanic boulders etched with ancient images of dragonflies, serpents and masked men.

The highway would open a path to thousands of acres of homes being built on the other side of the Petroglyph National Monument, a 17-mile ridge northwest of Albuquerque's downtown area.

"Our cultural areas are being sacrificed to make it easier to live here," said Steve Juanico, vice chairman of the All-Indian Pueblo Council.

In the next 25 years, Albuquerque is expected to grow by at least 50 percent, to more than 1 million people. With the city's growth blocked by the snowcapped Sandia Mountains to the east and Indian reservations to the north and south, developers say they have little choice but to look on the other side of the Petroglyph.

Those who support the quarter-mile highway extension include residents who fear motorists in the new 60,000-person subdivision will otherwise use existing back roads through their neighborhoods.

"We are not going to allow 40,000 cars to go through our neighborhood," said Larry Weaver, president of Paradise Hills Civic Association.

Sen. Pete V. Domenici (R-N.M.) attached the proposal for the road extension to legislation seeking emergency appropriations for military action in Iraq. The full Senate could vote as early as this week. The legislation would authorize the road; the city would bear the cost, about $13.5 million.

The highway would cut through an 8.5-acre corner of the monument, destroying about a half-dozen of the park's 15,000 petroglyphs, most of which are about 2,000 years old, park officials say.

Indian tribes say that for religious reasons, they would prefer the art be destroyed rather than picked up and moved, according to Judith Cordova, superintendent of Petroglyph National Monument.

Opponents of the project include Mayor Jim Baca, conservation groups, National Park officials and tribal leaders, who say the highway would encroach on sacred ground once inhabited by their ancestors.

The auto and noise pollution caused by the road would be similar to having a freight train chug through, said Al Eisenberg, a deputy director at the National Parks and Conservation Association in Washington. Domenici, who in 1990 helped have the site designated a national monument to protect the etchings that rest at the foot of five extinct volcanoes, said the highway cuts through such a small portion that it will do little harm.

"I think everyone knows that I am the one who created this monument and I am the one who wants to preserve it," said Domenici, a former Albuquerque mayor. "But it is time to give Albuquerque the choice to build that road if they want to."