The most emotional moment of a visit to the prehistoric cave of Lascaux in southwestern France a few weeks ago was seeing handprints of the humans who created the most beautiful art of the Stone Age. They really were there, 15,000 years ago.

Caves decorated with art from the late Paleolithic period, approximately 10,000 to 30,000 years ago, have been found only in France, Spain, Italy, Portugal, Russia and Mongolia. The largest cluster of Paleolithic art caves dot the Dordogne department of southwestern France the Vezere Valley, which is honeycombed ,with limestone caves and towering cliff shelters eaten out by glaciers and underground rivers as long as 140 million years ago. In this underground network, with constant temperature and humidity and isolation from light, the art has been very well preserved.

The most exciting sites open to visitors in the Dordogne include Lascaux, Font-de-Gaume, with drawings of bison, horses and deer; Combarelles, where Stone Age people left more than 300 engravings, and Cap Blanc, offering 14 animals gracefully sculptured in deep relief.

Cave art had been seen by villagers as least as far back as the 16th century, according to graffiti in the vast cavern at Rouffignac. But it was assumed to be modern until an explorer announced in 1880 that the paintings in the Altamira cave were prehistoric.

The notion of art as ancient as 30,000 years before the birth of Christ was met with skepticism on the ground that it conflicted with Christian belief. Only in the 20th century did scientists agree that humans indeed discovered how to artfully draw, sculpture and carve engravings during the Stone Age.

The Louvre of all the caverns is Lascaux. The cave entrance, less than a mile south of Montignac on the Vezere River, was sealed from harmful air for centuries by landslides. After trees covering the entrance were uprooted by a storm, four teen-agers seeking buried treasure discovered the cave in 1940.

Opened to tourists in 1948, Lascaux had to be closed in 1963 after green algae and white calcium deposits attacked the paintings. An exact copy built in cement nearby was inaugurated in November 1984. The cement cannot be harmed by bacteria and outside air and the paintings are covered with a transparent film.

Contrary to widespread belief, the original Lascaux, guarded by a wire fence and two German shepherds, can be seen by qualified people. Applicants connected with science, journalism, teaching, art, museums, even politics, have received invitations after waiting for months.

On an authorized visit one recent day, a guide, Jacques Marsal, led the way past the dogs and wooden towers with instruments that record humidity, temperature and air pressure in the cave, monitored by the Pasteur Institute in Paris. Visitors must wet the soles of their shoes in antiseptic and descend to the dark, cold cave through three anterooms that keep out air. Then the electric lights go on, and the stereotype of the Stone Age brute is crushed. The cave gleams with delicate drawings in ocher and brick red, outlined in deepest black by artists who were obviously sensitive people. Deer with graceful horns, drawn with sensual lines, recall works of Picasso. The guide’s flashlight plays on a splendid herd of deer, apparently clambering out of water, each with a different expression, each in a different position.

On the cold stone walls, a calf stumbles before a three-sided square that could depict a trap. A horse falls over a cliff, its face showing fright, possibly depicting organized stampedes to slaughter animals.

”The artists painted the outline of each animal all in one movement without hesitation, quite a feat,” says the guide.

The final shock is emerging from the Stone Age cave to see white trails from jet fighters crisscrossing the blue sky. A two-minute walk downhill stands Lascaux II, the cement reproduction built by the owner of the land and the state, now the proprietor.

Molded above ground by 12 Brazilian, Greek and French sculptors over nine years, the cave is a feat in itself as the cement truly resembles rock. A French artist worked seven years with prehistoric tools and pigments to copy the paintings from photographs. The copiers even repeated holes where the prehistoric artists had inserted logs to stand on so they could reach a high ceiling to paint a circle of horses reminiscent of Chinese art.

The reproduction is impressive. But the ancient Lascaux, like any original artwork, is worth the wait. Lascaux II lacks the impact of antiquity, and the drawings appear flat because the real Lascaux walls glisten with crystals.

Some 200 paintings and 1,500 engravings decorate Lascaux I, which is 819 feet long. Lascaux II, 131 feet long, displays 100 or so paintings and no engravings.

Those startling handprints are a frequent motif in art of the late Paleolithic period. Handprints fringe paintings in the Pech Merle grotto, including one of a black polka-dotted horse. Two hundred fifteen handprints, usually of the left hand, decorate the Gargas cave in the Hautes-Pyrenees department near Spain.

Experts say 11 footprints at Pech Merle were those of a woman and child. They believe women and children often visited the caves to see the art, or to worship. The caves are believed to have been sanctuaries, devoted to the worship of animals, magic or the hunt, but scientists do not know for sure. The guides emphasize that prehistoric people were not ”cave men.” Because of the dampness of grottos and the need to build fires, Cro-Magnon people lived only at cave entrances, in minuscule caves or under overhangs of giant cliffs.

Patterns emerge in their art. Most of the subjects are grass-eaters such as horses, bison, deer, reindeer and ibex. Less numerous are meat-eating mammoths and rhinoceroses, which once roamed France, boars, wolves and fox, plus fish, birds and reptiles. A fish was engraved on the ceiling of a riverside shelter north of Les Eyzies, a Dordogne town dotted with prehistoric sites that calls itself the Prehistoric Capital of the World.

Drawings of humans are rare and not realistic. Men appear more often than women (although many prehistoric statuettes of women have been dug from sites throughout the world). In Lascaux, a man falls dead before a bull pierced with a spear, its entrails dangling. Arrows were thrust into men drawn at Lascaux, Pech Merle and Cougnac, north of Cahors. Evidence of war? Experts say flints have not been found in Paleolithic skeletons, but they have in later Neolithic graves after agriculture was discovered and people became property owners, and thus could have been defenders and aggressors.

The Cro-Magnons painted under the light of small stone lamps, which have been found in cave digs. They applied charcoal, ocher or red and yellow pigments of oxidized iron with brushes or their fingers or dabbed on colors with fur or blew them through tubes. Engravings were made with bone, horn or stone.