AT the top of the United States, 250 miles above the Arctic Circle, geologist David Hite kneels down in the tundra to crunch up and sniff a piece of soft, dark brown rock. "You've got everything here that you'd want to tell you there's oil accumulation," says Mr. Hite, an employee of the ARCO company who started work in Alaska when large amounts of oil were first discovered 23 years ago.So far, however, whatever oil there is remains buried thousands of feet beneath the permafrost, untouchable unless Congress gives oil companies the go-ahead to explore, develop, and produce. For this is the Arctic National Wildlife Refuge - where animals are supposed to come first, where 180,000 caribou and more than 100 species of birds migrate, where musk ox and Arctic foxes and polar bears live in a fragile environment the Wilderness Society calls "the American Serengeti" because of its biological div ersity. When lawmakers expanded the refuge to 19 million acres in 1980 (and declared 7.3 million acres of that to be wilderness), they also set aside 1.5 million acres along the coastal plain as a study area and directed the United States Department of the Interior to report back on the possibilities for oil development. In 1987, the secretary of the interior concluded that oil and gas activities should proceed, and that this could be done "in a manner consistent with the need and desire to conserve the area's s ignificant environmental values." The words "consistent with" are open to wide interpretation and considerable debate, and it may be that in the end, says Alaska state Sen. Drue Pearce, "the decision comes down to aesthetics - in a wildlife refuge, do you want to see the zigzag of a pipeline?" To stand on the contested part of the refuge, with the Beaufort Sea to the north and the rugged Brooks Mountain Range to the south, is to understand the meaning of the word "vast." There is a stillness and beauty here that is unique. This time of year, when the sun never fully sets, there are wildflowers and burrowing squirrels popping up to eyeball visitors. Herds of caribou, looking a bit moth-eaten as they shed their winter coats, move along with their calves, sometimes running to get away from the mo squitoes and other insects. The average summer temperature is in the 40s (F), but can reach into the 80s. Soon it will drop well below zero as the sun falls beneath the horizon for three months of frigid darkness. There is very little rainfall (10 inches a year), but the three-foot-thick tundra is a spongy, easy to damage wetland. "It is one of nature's harshest environments - and one of the most vulnerable," according to Lisa Speer, senior scientist with the Natural Resources Defense Council. "Any physical disturbance, even tractor tracks, can scar land for decades. Plants are more sensitive to air pollution than species in warmer climates. Toxic substances persist longer in the environment. And the impact of oil spills is more far-reaching and long-term than in more temperate climates." "Once the thermal balance is destroyed, it may take years to stabilize," warns a report by the Eskimo-owned Arctic Slope Regional Corporation, which owns the subsurface and mineral rights to 92,000 acres within and adjacent to the coastal plain study area. "During that time, ponds may develop as ice wedges melt and soils subside, altering terrain ... or, in extreme cases, resulting in erosion." Nevertheless, the Inupiat Eskimos who control the corporation believe that oil exploration should proceed and (assuming economically recoverable reserves are established) that development and production should follow. [See related article.] Whether that happens could depend largely on the track record of oil development about 70 miles west of the wildlife refuge along Prudhoe Bay, the largest oil field in the US. Members of the US House of Representatives Merchant Marine and Fisheries Committee will be in Alaska next week to inspect the refuge and oil facilities along the North Slope, and also to hold a hearing in Anchorage. The Senate is likely to vote on the matter in September, and the House shortly thereafter. There is no doubt that oil development has impacted some of the North Slope ecosystem. According to the Alaska Department of Environmental Conservation, such activities each day produce more than 4,000 cubic yards of solid wastes and 50 million gallons of liquid wastes. Most of the liquid is water brought up in the drilling process, but some of the fluids contain acids, caustics, solvents, and salts. Most of the solid waste is drilling mud and cuttings. The state agency reported last November that storage vapor tanks have the potential to produce over 4,000 tons of hydrocarbons annually, and turbines at North Slope facilities can emit up to 90,000 tons in nitrogen oxides and as many as 618 tons in sulfur dioxides each year. (Oil officials say their facilities release less than 20,000 tons of nitrogen oxides a year and sulfur dioxides are "below detectable limits.") Much of the liquid and solid waste is reinjected into the ground, which is a generally acceptable practice in northern regions. (The oil comes to the surface through artesian pressure, not pumping, and the injected water keeps pressure on the reservoir.) State officials paid little attention to drilling practices until the mid-1980s, when new regulations were issued. Since then, reports Bradley Fristoe of the environmental conservation department, "realization of unacceptable practices has caused a renaissance of ideas to improve the handling of drilling wastes." Oil companies also have improved their construction and drilling practices over the years to reduce the "footprint" on the tundra caused by roads, oil production facilities, and support services. For example, instead of building gravel roads to remote sites for maintenance, roads are built of ice in the winter. Heavy equipment, which might otherwise have damaged the tundra, can move over the roads, which then melt in the summer. Heated buildings and warm oil pipelines are built on pilings to prevent thawing of the permafrost. Vehicles, called "Rolligons," with fat tires that exert less force per square inch than the human foot, help reduce tundra impact. New directional drilling techniques allow more well bores to range out horizontally from a single well pad. This means individual wells can be clustered as close as 25 feet apart instead of spread out 120 feet between each one. BP Exploration (Alaska) Inc. has developed a ball g rinder that grinds drill cuttings into particles small enough to inject beneath the permafrost. Alaskan environmental officials call this "a major improvement." While support services for Prudhoe Bay, located at nearby Deadhorse, cover more than 1,000 acres (and even industry supporters acknowledge they are a mess), such services at Kuparuk occupy just 55 acres. Looking ahead to the day when Alaska runs out of petroleum, oil companies are investigating different methods of revegetation and other forms of tundra rehabilitation. The Interior Department estimates that the oil production footprint at the wildlife refuge (roads and gravel pads) would total 12,500 acres. But Scott Ronzio, manager of environmental sciences for ARCO Alaska Inc., says: "We believe that's 1970s technology, and in fact it would be much less." Mr. Ronzio notes that while the older facilities at Prudhoe Bay use 2 percent of the land space for roads and pads, the newer Kuparuk facility nearby uses just 1 percent. "It's a much better organized and managed pl ace," he says. "What the environmental community refuses to acknowledge are the improvements in oil exploration and development," says Ronzio. "Their criticisms are based on past behavior and practices." In a joint report, three environmental groups (the Natural Resources Defense Council, the National Wildlife Federation, and Trustees for Alaska) earlier this year charged that North Slope oil facilities have resulted in the "the direct loss of over 11,000 acres of habitat," plus another 31,000 acres associated with construction of the 800-mile Trans-Alaska Pipeline. The report adds: "Thousands of additional acres of habitat within the oil fields have been lost or altered by indirect impacts, including flooding caused by impoundments associated with roads and pads, dust which kills vegetation and alters local habitat, thermal erosion of permafrost caused by disturbance of tundra vegetation, pollution from oil industry waste, and fragmentation of habitat by roads, pipelines, and facilities." Despite improvements in industry operations at the Kuparuk and Endicott oil fields, say the environmental groups, "most environmental problems have not been solved or ameliorated to a significant degree." "These improvements," the report goes on, "will not change the fact that petroleum industry development in the refuge will cause extensive habitat destruction, pollution, and attendant impacts." One thing working in the industry's favor is the increase in the caribou herd around drill sites since oil exploration began in Alaska. Starting in the early 1970s, the Central Arctic Herd grew from 3,000 to 16,000. Many caribou can be seen wandering through the oil fields or gathering underneath buildings to stay cool and thus avoid summer mosquitos. It's quite usual to see Arctic foxes in the oil fields as well as geese and other water birds. The industry doesn't take any particular credit for the increase in caribou herd size, but cites it as evidence that petroleum production can coexist with animals. Wildlife specialists say the increase may be due to weather patterns and natural cycles in the herd, as well as hunting restrictions and the sharp decrease in natural predators (especially wolves) since oil development began. What is true for developed areas of the North Slope may not hold true for the wildlife refuge's coastal plain, some experts point out. Canadian Wildlife Service biologist Don Russell predicts that "displacement from calving sites in the [coastal plain] area will undoubtedly reduce calf survival in the Porcupine caribou herd" (so-named because it migrates back and forth across the Porcupine River). The Porcupine herd's calving area is much more concentrated than that for the Central Arctic herd, he notes, and "unlike the Prudhoe Bay development, where caribou movements run parallel to a pipeline/haul route, a pipeline in the [coastal plain] area would bisect the critical caribou range." Federal agencies have approved oil lease sales in the coastal plain, although the US Fish and Wildlife Service has called it "the center of wildlife activity for the entire refuge." "We as an industry can perform to very high standards," says ARCO's Scott Ronzio, looking out over the tundra on the Arctic National Wildlife Refuge. "But that's not the central question. The central question is, do you want this kind of activity out here? It's a question of relative values, and that's very, very difficult."