When the Lewis and Clark expedition arrived at the Three Forks of the Missouri River, July 27, 1805, they were at what Meriwether Lewis described as "an essential point in the geography of this western part of the continent."

It is the place where the Jefferson, Madison and Gallatin Rivers merge, (named for then-president Thomas Jefferson, and the secretaries of Treasury and War), and where the Missouri River is born amid a tangle of sloughs and creeks.Of this mountain valley (today part of west-central Montana) Meriwether Lewis wrote glowingly: ". . . the country opens suddenly to extensive and beautiful plains and meadows which appear to be surrounded in every direction with distant and lofty mountains."

It was also the place where Sacajawea the Shoshone wife of Touissant Charboneau, had been captured by a Minnesota raiding party six years earlier.

In 1976, the Three Forks was set aside as the Missouri Headwaters State Park, part of the Bicentennial fervor, which also saw monuments to Lewis and Clark erected at Ft. Benson, Mont., and at Clark's Fork, south of Dillon.

At the Missouri Headwaters State park, a handful of acres encompasses a small campground and an attractively landscaped picnic area, while a low picket fence marks a poignant mass grave of the now defunct river town of Gallatin. All 26 children buried there were victims of black diptheria.

When I asked a campground manager at nearby Three Forks, Mont. (the town) what was to be seen at the Missouri Headwaters State Park, he replied: "Nothing but a bunch of old plaques."

True, in part. At the Missouri headwaters, you approach the place with a sense of history.

One of those "old plaques" portrays Sacajawea pointing the way for the two captains, a romanticism that persists to this day.

Credible historians tell us she was never a guide, but deemed useful as an interpreter and for the horses her people, the Snakes, could provide. In other ways, however, she proved her worth.

Picking your way through prickly pear cactus along a limestone ridge above the Gallatin, it is possible to see this historic site in Lewis' own eyes.

He wrote in his journal: "I . . . walked up the S.E. fork about 1/2 mile and ascended the point of a high limestone cliff from whence I commanded a msot perfect view of the neighborhing country . . . between the S.E. and middle forks a range of lofty mountains ran their snow clad tops above the irregular and broken mountains which lie adjacent to this beautiful spot."

At the Three Forks, the Corps of Discovery was at the half-way point in their 4,000 mile journey to the Pacific, and had recorded things no other white man had seen.

The northern plains of the time were the American steppes, rife with wildlife, particularly "emence" herds of bison. Lewis and Clark were the first to describe the mule deer. They called the bighorn an ibex, and the pronghorn a "beardless goat" or antelope.

The vicious spines of the plain's prickly pear cactus tore at their feet, and was as great a nuisance as the swarms of midges and "musquetors."

Even so Lewis found time to admire its aesthetic qualities. "The prickly pear . . . forms one of the beauties as well as the greatest pests of the plains," he wrote. "The lambs quarter, wild cucumber and san rish and narrow dock are also common here."

He also named the clustered blooms of a member of the Lily family Bear Grass, presumably because he saw a number of grizzly bears walking through it.

Sometimes called a brown bear, sometimes a white bear, sometimes a "grisley" the journals are full of encounters with this most ferocious of American predators.

"Bratton . . . had shot a brown bear which immediately turned on him and pursued him a considerable distance . . . I went out with one man, Geo Drewer & killed the bear, which was very large and turrible looking . . . We Shot ten Balls into him before we killed him . . ."

On a trip last summer to Glacier National Park my wife and I stopped at the Many Feathers Trading Post between St. Mary and Baab on the Blackfoot Indian Reservation.

A one-room shack of rough-sawn boards with a teepee in back, and advertising "Fresh Fish," it nonetheless caught Linda's eye. She has an affinity for Indian art and we were on a collecting trip.

Once inside, I was intrigued by the man behind the counter. He was a strapping individual of Blackfoot descent with a face as craggy as the surrounding mountains. An enormous St. Bernard-Shepard mix, lay curled on the floor.

He gave his name as Richard and said he was a silversmith by trade. The dog was Kiowa. I asked, "You hunt bear with him?" "Sometimes," he grinned, as the subject turned to the grizzly.

I mentioned a photographer had been killed by a female with a cub earlier that summer near Many Glacier. "We've had three people killed," he said nonchalantly. "A few bones was all that was left of one of them."

"Sometimes we have to kill several bears to get the right one. However, we don't hunt them down without good reason," he was quick to add.

Until decimated by smallpox in 1837, the Blackfeet were the terrors of the plains, feared as much by other tribes as the grizzly bear.

In fact, among the Mandans and Minnetarees with whom Lewis and Clark had wintered, counting coup (touching) a Blackfoot warrior brought as much honor as killing a grizzly.

The Blackfeet were the only Indians fought by the expedition and the incident is blamed by some for the implacable hatred held by the Blackfeet for the Americans during those early years.

When I attempted to recall the incident I said to Richard," In typical Indian fashion, I suppose they went for the horses." "No, it was their guns," he corrected.

The encounter, described in Lewis' journal, occurred on the Marias River, on their return trip in 1806 when he and his men became uneasy traveling companions of a hunting party of Piegans, one of four tribes of the Blackfoot Confederacy.

One warrior was stabbed through the heart by Rueben Fields, and another shot "through the belly" by Lewis himself.

However, he forbid Geroge Drewyer, a hunter and civilian interpreter, to shoot another "as the Indian did not wish to kill us." The rest fled across the plains, leaving behind bows, saddles, quivers of arrows, shields and other items.

George Drewyer returned to the Missouri headwaters in 1808, in the employ of Manuel Lisa, an early entrepreneur of the fur trade. Out with a small hunting party, he was ambushed by Blackfeet and although he fought furiously, he was killed by vengeful warriors.

The Blackfeet also caught John Potts and John Coulter on the Jefferson River, both former members of the Corps of Discovery. Potts was riddled with arrows, but Coulter was stripped and told run for his life. His escape is the stuff of legend.

With other tribes, the expedition fared better. When bidding farewell to the Nez Pearce Indians, who accompanied them on their return trip through the Bitterroot Mountains, Lewis wrote: "I gave the chief a medal of small size; he insisted on exchanging names with me according to their custon . . . and I was called Yo-me-kil-lick which is interpreted as the white bear skin foalded." They had honored him by naming him for the grizzly.

Outward bound, the Corps of Discovery traveled some 500 miles out of their way as they poled their clumsy dugout canoes up the Missouri, and its tributaries, the Jefferson and Beaverhead in a futile search for a river passage to the Pacific.

But for a chance meeting with Sacajawea's people, they might have starved in the Bitterroots where there was little game. The homeward journey, however, was eased by horses acquired from the Nez Pearce and first-hand knowledge of the land ahead.

In Montana, the Lewis and Clark's Trail (as marked on the official state map) begins at the Montana/South Dakota line, near the confluence of the Missouri and Yellowstone Rivers. From this point, U.S. 2 parallels the Missouri River westward to Fort Peck, Mont., where a massive earth-filled dam impounds the river.

Beyond Ft. Peck, the highway arcs northward not touching the Missouri until reaching the historic post at Fort Benton, a distance of over 200 miles.

Between Ft. Benton and the head of the reservoir, 149 miles of Missouri bottomland remains pristine. Designated part of the National Wildlife and Scenic River System in 1976, it has changed little since Lewis and Clark's time.

By boat, it is possible to camp where they camped, and to be awed as they were by a chaotic landscape of weirdly eroded bluffs, buttes and cliffs known as the Missouri Breaks. For the first time, DeVoto wrote, the word beautiful appears in their journals.

As a trading post and head of steamboat navigation on the Missouri, Ft. Bennion played a key role in settlement of the Northwest from 1860-1887. The Grand Union Hotel at 14th and Front St. is a Montana landmark. The adobe walls of the old fort yet remain.

Credit for the discovery of the Great Falls of the Missouri is due Meriwether Lewis who wrote in his journal, ". . . the Lard bluff is a smooth, even sheet of water falling over a precipice of at least eighty feet . . . the remaining part of about 200 yards on my right forms the grandest sight I ever beheld."

Today their beauty and spectacle have been diminished by power installation.