Ridge by ridge and crevice by crevice, the heart of the vast central Idaho wilderness has been blackened by a series of forest fires this week that continue to defy a massive national effort to contain them.

One of the worst outbreaks, a blaze set accidentally by a camper, was raging on more than 56,000 acres today along the middle fork of the Salmon River, along the route taken by President Carter on his raft trip last year.

tthe river, a popular vacation spot for thousands of adverturesome Americans, was closed this week to rafters. Forest Service officials banned air travel over the area and have closed most forests to campers.

More than 1,000 firefighters from as far as Alaska, Arizona, Maine and Georgia, are battling the blaze in the Idaho Primitive Area. The Mortar Creek Fire, as it is called by U.S. Forest Service officials, was started July 26 by an unidentified vacationer who apparently failed to douse his campfire.

Seven other forest fires are still burning out of control in Idaho on wilderness tracts totaling some 120,000 acres. More than 135,000 acres of Idaho forests have already been destroyed, and, given the weather forecasts, a Forest Service official said today that the outlook for the next six to 10 days is "grim."

While Idaho has been the worst-hit state, this has been a week of major forest fires throughout the West in timber made fire prone by more than a month of temperatures in the 90s and 100s and almost no rainfall.

More than 8,000 firefighters, from almost every region in the U.S., are fighting fires in Montana, Oregon, Wyoming, Washington, California and Idaho.

They are being flown to the Boise Interagency Fire Center, the government's command post for fighting fires in the West, in fleets of chartered aircraft in a scene resembling a military maneuver.

The Boise Municipal Airport, site of the center, has seen scores of firefighting teams, many of them 100 or more strong, marching through it in orderly ranks dressed in yellow and red protective clothing. Crews at the center hand the newcomers axes, shovels and other equipment before they are quickly briefed and sent out to do battle with the fires.

A squadron of red-and-white DC6s and Lockheed Electras has been taking off around the clock to bomb fire-threatened ridge lines with water and orange colored fire-retarding chemicals. Old DC3s have been flying smoke jumpers who parachute into spots inaccessible by ground.

Damage in Idaho so far has been largely confined to forests in wilderness areas closed to the logging industry. The impact on logging has been accordingly minimal.

The firefighters have suffered scores of minor injuries, many of them caused by rocks exploding from the heat, but there has been only one death, which came early on in the two-week-old, 11,000-acre Ship Island fire elsewhere on the Salmon River.

Two houses were destroyed Wednesday near Bonners Ferry when an 800-acre fire reached its outskirts and for a while the town of 1,900 persons itself was threatened. But hundreds of residents helped professional firefighters halt one arm of the blaze two miles from the town.

The 50,000-acre Gallagher Peak fire on the Idaho-Montana border may be contained by late Friday, the Forest Service says, and more than a dozen small blazes have been brought under control since the week began.

But the major fires continue to burn in Idaho, with firefighting officials unable to do much to stop them because of the dryness of the timber and high winds. Also hampering their efforts is the ruggedness of the terrain and the complete lack of roads in the areas because of their "wilderness" classification.

Amid the praise for the efforts of the firefighters, there has been some criticism, most notably that of idaho Gov. John V. Evans, who said the Forest Service's reliance on its "prescription fire" formula for tackling fires may have resulted in some faulty decisions.

Evans said that the Gallagher Peak fire was a "mistake" and that Forest Service officials, who at first thought it would be confined to a 300-acre area, allowed it to burn under the "prescription" formula while neglecting to reckon on the dryness of the surrounding stands of lodgepole pines.

Under the "prescription" formula, certain fires are allowed to burn freely if officials think they can be easily contained and used to clear away stands of diseased trees, creating new habitats and food resources for wildlife.

The Gallagher Peak fire burned within the 300-acre zone until last weekend, when it suddenly burst out and exploded into a 50,000-acre area, giving off the energy equivalent, said Fire Center Intermountain Area fire director Richard Montague, of "several atomic bombs."