On the day he reached the "two forks" Lewis wrote in his journal, "I do not believe that the world can furnish an example of a river running to the extent which the Missouri and Jefferson's rivers do through such a mountainous country and at the same time so navigable as they are".

Lewis was describing a landscape that has been millions of years in the making! Over that time, the Earth's crust in this area has been pulled apart to form a landscape of towering mountains and broad valleys.

The placid rivers that follow these valleys made the notion of a Northwest Passage a possibility. Unfortunately for the Corps of Discovery, the geology to the west of the Great Divide produced deep canyons with raging rivers, ending all hopes for a safe "communication across the continent by water."

The Geological Time Scale (not shown to scale)

Divisions of geological time were defined in the 19th Century by major changes in the fossil record.

Most of the boundaries are marked by worldwide extinction events.

Numerical dates were added in the 20th Century using modern rock-dating techniques.

Precambrian 4500 million years ago: Earth began. Formation of igneous and metamorphic rocks.

Paleozoic Era 542 million years ago Deposition of sedimentary rocks.

Mesozoic Era 250 million years ago Deposition of sedimentary rocks, folding and thrust faulting.

Cenozoic Era 66 million years ago Deposition of sedimentary and volcanic rock, extension of the Earth's crust and formation of the Red Rock Valley and Tendoy Mountains.

Making of the Landscape

On August 17, 1805, the historic meeting of cultures took place in this valley. The valley started forming about 4.0 million years ago as extension of the Earth's crust produced a fault that dropped the Red Rock Valley down and uplifted the adjacent Tendoy Mountains. Although this fault is considered by geologist to be active, it last ruptured the ground surface some 3,000 years ago. Fortunately for the Corps of Discovery, there was no activity on this fault on August 17, 1805.

Erected by Reclamation, University of Montana, Western.

Following an Indian road on the east side of the Beaverhead River, Captain Meriwether Lewis, along with three men, arrived here on August 10, 1805 and stopped long enough to lunch on freshly killed deer. Several days earlier, Lewis struck out ahead of the main party in search of Sacagawea's people, the Lemhi Shoshoni. He called these high rock formations in front of you "rattle snake clifts" after the large number of snakes they encountered here.

Passing through here five days later on August 15, 1805, Captain William Clark, with the main party, encountered the same resident rattles as they pulled their heavy canoes against the current of the river.

Rattlesnake Cliffs

Rising to a height of around 600 feet above the valley floor, these cliffs are composed of 50 million year-old volcanic rock that has been uplifted along the Blacktail fault. Weathering of this often badly fractured rock allows numerous little hollows to form creating excellent dens for snakes.

On August 10, Captain Meriwether Lewis wrote, "Here we kindled a fire....and eat a haisty meal...from the number of rattle snakes about the Clifts at which we halted we called them the rattle snake clifts."

Five days later on August 15. 1805, Clark noted in his journal , " In walking on shore I saw Several rattle Snakes and narrowly escaped at two different times, as also (Sacagawea) when walking with her husband on shore... This moutn I called rattle Snake mountain..."

On this same day Joseph Whitehouse, who was traveling with Clark mentioned, "some of our party catch'd a quantity of fine Trout...Capt. Clark was near being bit by a Rattle snake...it got between his legs, whilst he was standing fishing, he killed it, & a number of the same kind this day."

Few points along the route of the Lewis and Clark Expedition have the significance of this site, now beneath the waters of Clark Canyon Reservoir. Noted on their maps as "Fortunate Camp", the Lewis and Clark Expedition journeyed here hoping to obtain horses from Sacagawea's people, the Lemhi Shoshoni.

Following an Indian trail in advance of the main party, Captain Lewis first reached this site on August 10, 1805. Two days later, he crossed the Continental Divide west of here, and met the Lemhi Shoshoni. Although suspicious of the white men, they returned with Lewis to meet the rest of the party, arriving back here on August 17, 1805. At the meeting, Sacajawea was reunited with brother, Chief Camehwait, whom she had not seen for five years.

Through her, Lewis and Clark negotiated for horses and a guide - critical for the expedition's journey across the mountains to the Columbia River drainage. In exchange, the Shoshoni were promised that future trade would include guns and ammunition - critical for their defense against enemy tribes.

In July 1806, Clark and his party returned here to retrieve canoes and supplies they had cached the previous year in preparation for the return trip down the Missouri River to St. Louis.

"...it was mutually advantageous to them as well as to ourselves that they should render us such aids as they had in their power to furnish in order to haisten our voyage and of course our return home. that such were their horses to transport our baggage without which we could not subsist and that a pilot to conduct us through the mountains was also necessary if we could not decend the river by water." -- Captain M. Lewis, August 17, 1805

Where is "Fortunate Camp"?

"immediately in the level plain between the forks and about 1/2 a mile distance from them stands a high rocky mountain, the base of which is surrounded by the level plain; it has a singular appearance." -- Captain M. Lewis, August 18, 1805

Today, this "singular mountain" forms the large island you see in front of you, marked on their map between the forks. The actual site of Camp Fortunate is now under water, half-way between this island and the dam. Look at the map for its symbol δ just before the forks to the left.

"We now found our camp just below the junction of the forks on the Lard. side in a level smooth bottom covered with fine terf of green-swoard." Captain M. Lewis, August 17, 1805

Erected by Montana Bureau of Reclamation.

Sidney Edgerton arrived at Bannack from Ohio in September 1863 to begin his appointment as Chief Justice of the Supreme Court of Idaho Territory. The massive territory encompassed Idaho, all of Montana, and the western half of Wyoming, with the capital at Lewiston, Idaho. Edgerton became convinced that the region's gold discoveries created the need for government closer at hand. Carrying two thousand dollars' worth of gold dust sewn into his clothing, he undertook the treacherous journey to Washington, D.C., where Congress was considering creating a new territory. Edgerton advocated that Montana's western boundary fall along the Bitterroot Mountains, rather than on the proposed Continental Divide. Thus, it was Edgerton who won the Bitterroot and Flathead Valleys and the future wealth of Butte for Montana. After Congress created Montana Territory on May 26, 1864, President Abraham Lincoln appointed Edgerton its first governor. However, Lincoln failed to appoint a territorial secretary, the only official authorized to spend federal money. Edgerton kept the territory afloat with is own personal funds. On February 2, 1865, the territorial legislature established Edgerton County as one of Montana's original nine counties. The county name did not last long. Edgerton was a strong, outspoken Republican abolitionist, whose belief is equal rights was unpopular with the territory's Democratic majority. Edgerton resigned as territorial governor, departing for Akron, Ohio, in September 1865 where he practiced law util his death in 1900. In December 1867 the territorial legislature voted 7-0 to change the name of Edgerton County to Lewis and Clark County. Bitter partisan politics denied Edgerton the recognition he deserved as the "Father of Montana."

Erected 2015 by Montana National Register Sign Program.

Lewis and Clark Trail 1806

First important gold camp 1862

Scene of vigilante activities 1863

First capital Territory of Montana 1864-1865

First county seat of Beaverhead County 1864-1881 In grateful memory of the early pioneers who founded our Commonwealth

Erected 1925 by Montana State Society Daughters of the American Revolution.

Bannack epitomizes the tough, primitive towns that sprang up with gold discoveries. Its story also illustrates a century of survival, through boom and bust periods associated with resource extraction and technological advances. On July 28, 1862, prospectors John White and company made a lucky strike, triggering Montana’s first major gold rush. Miners—many from Idaho’s crowded Salmon River diggings—swarmed over the Continental Divide. By spring 1863, Bannack had 3,000 inhabitants. The town saw six vigilante hangings, including that of its infamous sheriff, Henry Plummer. Briefly designated capital of the new Montana Territory in 1864, the first legislature met here in a crude log cabin. While other gold strikes stole Bannack’s initial population, the town rebounded in the 1870s and served as the Beaverhead County seat until 1881. The Masonic Lodge Hall/School (1874), Methodist Church (1877), and the Hotel Meade built as the Beaverhead County courthouse (1875) reflect this period. Evidence of hydraulic, dredge, and hard rock mining interrupt the landscape. Montana’s first quartz claims initiated hard rock mining here in 1862 and stamp mills soon operated alongside placer mining. Changing technologies produced new boom periods and other changes to Bannack. Electrification of the mines in 1930 brought electricity to the town. Despite its varied fortunes, the community held together while local mills operated sporadically until World War II. The State of Montana acquired most of the town in 1954, and a few residents remained until the early 1970s. Bannack features multi-period buildings spanning the primitive 1860s, urbanized 1870s-1880s, and early twentieth century. In 1961, Bannack earned status as a National Historic Landmark.

Erected by Montana National Register Sign Program.

By the time the Corps of Discovery passed through here, the "Valley of the Beaverhead" was already common ground for many Indian tribes. The Beaver's Head was a well-known landmark not only to the Shoshone but other Rocky Mountain tribes who passed through this valley on their way to and from buffalo country. In 1832, the fur-trapper, Warren Angus Ferris noted in Life in the Rocky Mountains,"Aware now of the vicinity of an Indian village (at the Beaver's Head)...some of our boldest comrades with our fleetest horses...rode off in the direction of that village...the village was composed of about one hundred and fifty lodges of FlatHeads, Pen-d'oreilles, and other..."

"we proceeded on passed a remarkable Clift point on the Stard. Side about 150 feet high, this Clift the Indians Call the Beavers head, opposit at 300 yards is a low clift of 50 feet which is a Spur from the Mountain on the Lard. about 4 miles... - Captain William Clark, August 10, 1805"

"the Indian woman recognized the point of a high plain to our right which she informed us was not very distant from the summer retreat of her nation on a river beyond the mountains which runs to the west. this hill she says her nation calls the beaver's head from a conceived remblance of it's figure to the head of that animal. she assures us that we shall either find her people on this river or on the river immediately west of it's source..." - Captain Meriwether Lewis, August 8, 1805

Prominent Exposure of Limestone

The Beaver's Head is a prominent exposure of limestone of the Mississippian Mission Canyon formation that rises above the flood plain of the Beaverhead River.

Erected by Camp Fortunate Chapter, Lewis and Clark Trail Historical Foundation and University of Montana Western.

The waters of the Beaverhead River opened this southern gateway to Montana through which have passed:

Ancient Indian Trail

Lewis and Clark Expedition 1805-1806

First Missionary, Father DeSmet 1840

Great Beaverhead Wagon Toll Road 1866-1880 (chartered by James Ryan and William Sturgis)

First Railroad into Montana, the Utah and Northern 1880

On this site stood the old toll house, toll gate and bridge nearby, Sturgis Post Office and Junction 1868, Ryan Post Office 1869 and T.M. Barrett Store 1874.

Erected 1935 by Daughters of the American Revolution Beaverhead Chapter.

This Plaque and Chimes Installed to the Glory of God in Memory of Beaverhead County Boys Who Gave Their Lives in World War II

Raymond Arrigoni • James Barlow • William Bender • Phil Burke • Thomas Butler • Frank Buyan • LaRue Cantrell • Clyde Casterline • Bob Farmer • Norman Featheroff • Paul Fidler • Roscoe Gordon • Roy Manson • Thomas Harris • Harlan Harrison • Elmer Heggeland • James Judge • Neil Keith • Joseph Kluesner • Reid Kochel • John McGanan • Alden Mast • Harry Neagmer • LaMarr Moore • Glen Mussetter • Don R. Nelson • Howard Nelson • Byron Orr • Darrell Peterson • Desmund Power • John Price • Hugh Radwell • Fred Rife • Leo Roland • Robert Rott • Harold Scriven • Walter Shaffner • Wesley Slovlin • Verde Smithies • Harry Spehar • Robert Spriull • Rudolph Swetish • Ralph Tope • Roy Tornelson • Kenneth Van Antwerp • Kenneth Welborn • Roy Wellington • Lloyd Whipple

This Plaque Sponsored by V.F.W. Post No. 4163

Chimes Sponsored by Baptist Church

Erected by V.F.W. Post No. 4163.

The prominent geological feature to the west is called Beaverhead Rock. On the afternoon of August 8, 1805, members of the Lewis and Clark Expedition pulled its canoes up the Beaverhead River toward the Continental Divide. They sighted what Clark later called a “remarkable Clift” to the southwest. Sacajawea recognized this large promontory and told the captains that her people called it “beaver’s head.”

Beaverhead Rock is composed principally of Madison Limestone. About 350 million years ago, a shallow sea covered much of Montana. Billions of tiny marine creatures thrived in the water and when they died their bodies settled into the muck on the sea bed. After about 10 million years of accumulation and many more millions of years of compaction this muck became the pale gray rocks that are known today as Madison Limestone. The limestone is common throughout Montana, eastern Idaho, northern Wyoming, and in the Dakotas. In Montana, the limestone beds range from 1,000 to 2,000 feet thick. Because in Montana’s dry climate Madison Limestone resists weathering and erosion much better than most other kinds of rocks, it forms many of the spectacular cliffs and ridges that make Montana so scenic.

Beaverhead Rock served as an important landmark not only for Lewis and Clark, but also for the trappers, miners, and traders who followed them into this area. It was known to many of them as Point of Rocks. In 1863, a man named Goetschius built a stage station on the "well-traveled, deep rutted road" between Bannack and Alder Gulch near here. It was part of the Montana-Utah Road, but was also known as Road Agents Trail because of all the robberies that occurred along it during the 1860s. In addition to changing tired horses for fresh animals for the stagecoaches, the station also served meals and provided a place to sleep for stagecoach travelers.

Geo-Facts:

The glaciated peaks of the Tobacco Root Mountains are on the horizon to the northeast. The range consists of a large granite batholith that pushed up through Paleozoic and Mesozoic formations about 70 million years ago.

The mountains to the east are the Ruby Range. Madison Limestone forms the peaks at the north end of the range, whereas the lower hills to the south are Precambrian basement rock. There are also outcrops of white marble in the range. Marble is a metamorphic rock that forms when limestone recrystallizes at high temperatures deep within the earth.

The Point of Rocks stage station was also known as Watson Station and included a hotel, saloon, and post office. It closed in 1881 with the arrival of the Utah & Northern Railroad. The dirt road at the base of the bluffs is the Montana-Utah Road.

Geo-Activity:

Can you see how Lewis and Clark might have thought Beaverhead Rock looked like a giant beaver swimming across a river? Try naming some of the mountains and other features you see from the highway after animals or parts of animals.

Erected by Montana Department of Transportation.

The End of Navigation

The Corps of Discovery's travel on the Missouri River came to an end here in mid-August of 1805. Lewis and Clark followed Thomas Jefferson's order to ascend the Missouri drainage as far as possible by boat and ran out of navigable water in the upper reaches of a tributary they called "Jefferson's River" (Beaverhead).

The Captains had counted on securing horses from Indians living in this region in order to make a portage over the mountains to the Columbia River drainage, yet the Corps had not seen any Indians since leaving the Mandan village four months earlier. Time needed for crossing the mountains before winter set in was slipping away. Lewis and three men moved on ahead of the canoes and crossed over the Continental Divide where they located a Shoshoni Indian band who happened to be Sacajawea's people. Lewis then returned to the "forks of Jefferson's river" where he waited for Clark and the canoe party. The Captains called this place "Fortunate Camp."

"Saturday 17th. A fine morning.

We proceeded on about 2 miles and discovered a number of the natives, of the Snake nation, coming along the bank on the South side. Captain Lewis had been as far as the waters of the Columbia river and met them there. We continued on about two miles further to a place where the river forks, and there halted and encamped after much fatigue. The water is so shallow that we had to drag the canoes, one at a time , almost all the way...

Here we unloaded the canoes, and had a talk with the Indians; and agreed with them that they should lend us some of their horses to carry our baggage to the Columbia river." - Sergeant Patrick Gass

" at twelve Oclock we set out and passed the river below the forks...most of the horses were heavily laden, and it appears to me that it will require at least 25 horses to convey our baggage along such roads as I expect we shall be obliged to pass in the mountains. I had now the inexpressible satisfaction of find myself once more under way with all my baggage and party." August 23, 1805 - Captain Meriwether Lewis.

The Start of the Portage

The failure to find an easy portage over the mountains meant leaving their canoes behind. While William Clark set out ahead to determine if the river (Salmon) to the west was suitable for travel by water, Meriwether Lewis stayed at the camp and prepared the Expedition for the portage (Lemhi Pass). The men fashioned pack saddles and harnesses using rawhide thongs and the blades from the oars and planks from storage boxes. Equipment and supplies were sorted and packaged. Some supplies and specimens were cached 3/4 of a mile downstream from camp. Lewis wrote in his journal on August 20th how they secured the seven canoes, to await their return trip.

"I also laid up the canoes this morning in a pond near the forks; sunk them in the water and weighted them down with stone, after taking our (sic) the plugs of the gage holes in their bottoms; hoping by this means to guard against both the effects of high water, and that of the fire which is frequently kindled in these plains by the natives."

The gauge holes in the bottom of the canoes were drilled by the men during construction to "gauge" the depth or thickness of the wood then plugged when completed.

William Clark recovered the canoes and supplies on the 8th of July, 1806, during the return trip from the Pacific.

The City Hall building was built in 1914. The ground where the building sits was purchased from David Robb for $4,450. It was designed by renowned architect Fred R. Willson and built by contractor William Reed. Construction began in April 1914 and was completed in November 1914 for a total of about $40,000, which include the purchase of the land, architectural fees and construction costs. The building originally housed the Police Magistrate and Police Lockup, Fire Department, Water Commissioner and offices of the City. The grand ballroom has been used throughout the years for various events, including dances, heavy weight boxing, fund raising and public speechs.

Erected by City of Dillon.

This monument design is taken from the small pocket compass carried by William Clark on the expedition. Clark’s compass was made by Thomas Whitney in Philadelphia.

Fortunate Chapter of the National Lewis and Clark Trail Heritage Foundation 2004

Montana Lewis & Clark Bicentennial

Erected 2004 by Camp Fortunate Chapter, National Lewis and Clark Trail Heritage Foundation.

The four buildings that make up this small historic district show the growth of Dillon’s city government. Buildings include ones constructed in the Progressive Era, the New Deal, and the 1960s, when the city built a shelter for one of its water wells. The 1914 city hall displays the Progressive Era’s optimism, practicality, and belief in government as a force for good. The building housed a variety of municipal functions, including the fire and police departments, water commission, and city clerk’s office; large openings onto East Center Street mark the former fire-engine bays. The design also included a city council meeting room, living quarters for firefighters, a municipal jail, and a large public auditorium. The latter provided space for lectures, dances, fraternal meetings, boxing and wrestling matches, and theatrical productions. Bozeman architect Fred F. Willson designed the dignified Romanesque Revival style building with decorative brickwork patterns, projecting arched hood molds, and fanlight windows. The effect was a building decorative enough to instill public pride and modest enough to indicate fiscal responsibility. As Dillon grew, the city expanded on the lots behind the main building. In 1936-37, using funds from the Works Progress Administration, a New Deal federal jobs program, a shop was constructed behind city hall. It served as a police garage, shop, and storage, and included space to house the jail’s female prisoners. When the city needed more space, particularly for fire equipment, this shop was added onto, and another garage/shop was built and added onto in 1945 and again in 1975.

Erected by Montana Historical Society.

Built in 1902, this building was the second location of the Dillon Implement Company, a company that was founded in August of 1886. The first location was north of the Union Pacific Depot on Montana St. The second building was constructed from stone quarried in the Frying Pan Basin about 9 miles north of Dillon. William Phillips was the manager and president of the Dillon Implement Company at the time the building was constructed. The Philips and Bond families were united in marriage in 1921 and the Dillon Implement Company remained in the same family for 72 years.

Carriages, wagons, saddles, harnesses, farm implements and windmills were among the early items available for sale to area ranchers and farmers. The company was known for stocking quality merchandise and honest business practices.

The building next door was built by Charles Phillips in 1916 of mold-formed concrete blocks. The downstairs was the Beaverhead Bank while the second floors of both buildings were joined by a long hall. They were commonly known as the Phillips Apartments.

Over the years the buildings have housed many businesses, including the original location of the Safeway grocery store, the Patagonia store and Sagebrush Sewing.

Dr. John Micha's vision and love of the historic downtown buildings in Dillon prompted the renovation of this building by Kreg Jones, Architect, and Kim Baker, Builder, in 2014

This tablet marks the site of the first public school building which was also used for the first court house-theatre and library in Dillon

Dedicated to the pioneers of the valley on the fiftieth anniversary of the founding of Dillon.

Placed by Beaverhead Chapter Daughters of the American Revolution

Erected 1930 by Daughters of the American Revolution Beaverhead Chapter.

Your observations are to be taken with great pains & accuracy, to be entered distinctly & intelligibly for others as well as yourself, to comprehend all the elements necessary

—President Thomas Jefferson

On August 13, 1805 William Clark took three compass readings from atop the rock before you. While looking out from this exposed limestone bluff he selected geographic landmarks as points on which to take bearings. His resulting maps became an important resource for future travelers.

The Corps of Discovery began their journey with no printed materials such as maps or reports to guide them through what is now Montana. In addition to the constant challenge of choosing which water route to take, they were also faced with deciding which of the countless land formations to plot and describe as they attempted to fulfill their mission. President Jefferson instructed Lewis to describe all features that could be positively identified by future travelers.

As you ascend Clark’s Lookout, observe the vastness of the surrounding area. When you reach the top, consider the view and decide which geological points you would include on a map. What features do you see that would help others navigate through this terrain 200 hundred years from now?

Historic Landmarks like Clark’s Lookout State Park preserve places where we can connect with the past. While the surrounding area has obviously changed, the landmarks on which Clark took bearings that day remain as he saw them.

Point of the Beavers head hill hears N24 E. 12 Ms. The course of the Wisdom River N25 W. The Gap at the place the river passes thro' a mountain in advance is 18 w 10 Ms

—William Clark

Erected by Montana State Parks.

This site was the pivotal point in the success of the Lewis and Clark Expedition. The party camped here in August 1805. They cached their boats and aided by the influence of Sacajawea obtained horses from her people the Shoshone Indians

The Great American epic of Lewis and Clark stands without parallel in the history of the opening of the West and the successful accomplishment was largely due to the guidance and loyalty of the Indian girl Sacajawea. -- Lara Tolman Scott

In midsummer, 1862, John White and party discovered gold on this creek several miles down stream. The first major gold rush to what is now Montana resulted.

Erected by Montana State Parks.

The Andrus Hotel was built to be a first-class establishment to serve the City of Dillon and to accommodate train travelers in the ares. Jesse M. Warren, a well known Butte Architect, designed the building for construction. Dar Hardware of Dillon was awarded the contract for heating and plumbing.

The three-story building accommodated a variety of businesses on the first floor and 65 sleeping rooms on the top two floors. The hotel featured a formal dining room and a cafe, as well as a bar named the Andrus Fountain. The Andrus was a popular gathering place for sheep and cattle buyers. The lobby included a long rectangular stained glass skylight and an automatic electric elevator.

A Great Dane dog named King Pharoah (sic) served as a bellhop to meet train passengers at the depot and carry their bags to the hotel. King Pharoah had his own overstuffed green leather chair in the hotel lobby.

Dr. John Micha's vision and love of the historic downtown buildings in Dillon prompted the renovation of this building by Kreg Jones, Architect, and Kim Baker, Builder, in 2014

This property has been placed on the

National Register of Historic Places by the United States Department of the Interior

The Big Island

Camp Fortunate was located near the base of the prominent island in Clark Canyon Reservoir. The singular mountain in the open plain that Meriwether Lewis described is a limestone rock outcrop that separated the "two forks of the Jefferson River" prior to submergence in 1964. The rock is prominently exposed today due to a combination of the uplift of the ground and the slow erosion of the limestone in the arid climate of southwest Montana.

Mississippian Limestone

South Montana was covered by a topical ocean some 360 million years ago during a time geologists call the Mississippi Period. This rock outcrop originated as seashells that accumulated on the bottom of this ocean. The shells were buried and cemented together to form a rock type called limestone. Geologists call this limestone the Madison Group.

A Tropical Paradise in Montana

It is amazing to envision that the place where you now stand was once a tropical marine paradise, occupied by fish, sharks, squid, corals, crinoids, brachiopods, bryozoans and many other marine animals.

If you look carefully at the rocks you will see the fossil remains of the most common animals that lived in this part of Montana some 360 million years prior to the arrival of Lewis and Clark!

Look at the sample of Mississippian limestone next to the sign and see if you can find the fossils shown in the photos below.

Corals

Corals are related to sea anemones, jellyfish and other animals with a sac-like body and tentacles with stinging cells. They live in a mineralized cup called a theca and they filter the water for live food. Most corals live in colonies, but many in the past lived as solitary animals. A fossil of a solitary Rugose coral is shown in the photo.

Brachiopods

Brachiopods are bottom-dwelling animals that use sticky tentacles to filter the ocean water for suspended food particles.. They usually fix themselves to the sea floor by a means of a fleshy stalk. Their two valves might remind you of a clam, but they are not closely related. Brachiopods have managed to survive on the Earth for about 600 million years!

Bryozoans

Bryozoans are twig-like animals that are very closely related to brachiopods. The "twigs" are actually colonies of animals that use sticky tentacles to filter the ocean water for suspended food particles. Although they look simple, they are very advanced animals with a nervous system, muscular tissue and a complete digestive system.

Crinoids

Crinoids are marine invertebrate animals that are related to starfish, sand dollars, sea-urchins and other animals with bodies that are organized into patterns of five (pentameral symmetry). Although they look like plants, their arms are lined with tube feet that are used to capture plankton. The most common parts of crinoids to be preserved as fossils are the pieces of the arm of animal (shown in photos).

The Geological Time Scale (not shown to scale)

Divisions of geological time were defined in the 19th Century by major changes in the fossil record.

Most of the boundaries are marked by worldwide extinction events.

Numerical dates were added in the 20th Century using modern rock-dating techniques.

PRECAMBRIAN 4500 million years ago Earth began Formation of igneous and metamorphic rocks.

PALEOZOIC ERA 542 million years ago Deposition of the Madison Group limestone during the Mississippian Period

MESOZOIC ERA 250 million years ago Deposition of sedimentary rocks, folding and thrust faulting

CENOZOIC ERA 66 million years ago Deposition of sedimentary and volcanic rock, extension of the Earth's crust and formation of the Red Rock Valley and Tendoy Mountains.

Erected by 3. Coral

Reclamation, University of Montana Western.

The Lewis and Clark Expedition passed this way going west August, 1805 and returning July, 1806.

‘Though the Pathfinder may die, the paths remain open.’

Beaverhead Chapter Daughters of the American Revolution. June 14, 1928

Erected 1928 by Daughters of the American Revolution Beaverhead Chapter.

Instruments for ascertaining, by celestial observations, the geography of the country through which you will pass, have been already provided. —President Thomas Jefferson

The data collected by Lewis and Clark is a striking indicator of their skillful use of navigational equipment. The Corps of Discovery was equipped with the most advanced navigational tools available, but rarely used them to help find their way. The equipment shown here is part of what allowed the Corps to successfully calculate their positions of latitude and longitude, distance traveled and to differentiate between true north and magnetic north.

For navigating the waterways to the Pacific Ocean they relied on three resources: talking with Indians, intuition and keen observational skills. Unfortunately for the expedition, they traveled through the current state of Montana without meeting any native people until Lewis met the Shoshone Indians in present day Idaho on August 13th 1805. Several days later, the expedition camped with the Shoshone at Camp Fortunate and traded for horses.

When they came to a river confluence they relied on information gained from previously encountered Indians. This information was combined with their general knowledge of river systems. The quantity of water flow, the nature of the terrain, luck, and instinct determined which current they followed.

The basic principles of navigation have remained largely unchanged. A combination of recognizable land features, advice from past travelers, instruments, maps and perhaps celestial observation give us confidence that we are following a route that will lead to our destination.

Erected by Montana State Parks.

The Martin Barrett House, built in 1912, was the in-town retirement home of prominent pioneer rancher, politician and philanthropist Martin Barrett and his wife Alice. One of the finest examples of early-twentieth-century architecture in Dillon, the Barrett House combines the grace and symmetry of the Colonial Revival style with the horizontal rooflines of the Prairie style. Born in Ireland, Martin Barrett arrived in Montana Territory in 1863, wisely choosing to make his fortune in the goldfields by raising stock at Horse Prairie. By 1871, he ran 2,000 head of shorthorn cattle on 4,500 acres. He was elected to two terms in the territorial legislature and was the Beaverhead County Stock Commissioner for six years in the early 1900s. He served on the Dillon School Board, but was defeated by his wife, who then served as a board member for the next twenty-two years. Martin Barrett also was a founding member and vice president of the Dillon State Bank. In 1921, he donated $100,000 towards the construction of a new hospital in Dillon, named for him as its major benefactor.

Erected by Montana Historical

Society.

It was acquire many years ago in the mountains southwest of Dillon, MT. The tree could be as much as 500 years old. The Sheepeaters placed a mountain sheep skull in the crotch of a tree, and over a hundred years or more the tree grew around it. Later another skull would be placed above the first one and eventually the tree grew around it also. There are four skulls in this tree.

This unique treasure is provided through the generosity of Ruth Berthelson of Dell, MT.

The Nez Perce camped near here on Horse Prairie Creek, Aug. 12 1877 following the Battle of the Big Hole Aug. 9-10. General Howard was summoned when beating drums arroused [sic] the citizens of Bannack. Women and children were quartered in the Meade Hotel where extra food, water and bedding were assembled. Dirt and log breastworks were thrown up at these two hill top sites but no attack took place. When Howard arrived the 14th, the Indians had left.

Interstate 15 is the latest in a series of roads that have traversed this area since prehistory. Although used for generations by Native Americans, the first recorded use of this route was by the Lewis and Clark Expedition on August 10, 1805. They named cliffs to the north of here after the scores of rattlesnakes they encountered on their trip upriver. With the discovery of gold at nearby Grasshopper Creek and Alder Gulch in the early 1860s, thousands of people came to southwest Montana to mine gold and to "mine the miners." The road originated in Corinne, Utah and traversed a series of high plateaus and narrow canyons on its way north to southwestern Montana. The road was the best route into the territory for the freighters who supplied the mining camps. Drawn by teams of mules or oxen, each wagon carried up to 12,000 pounds of freight. The trip from Utah typically took three weeks and a freighting outfit could usually make three or four round trips each year. South of here near Dell, the Montana-Utah Road branched into three separate trails that lead to Bannack/Deer Lodge, Virginia City and Helena. This section of the road terminated at Helena.

With the arrival of the Utah & Northern Railroad in 1880, the Montana-Utah Road became obsolete. In the 1920s, however, it again became an important travel corridor as U.S. Highway 91 and, in the early 1960s, as Interstate 15.

Erected by Montana Department of Transportation.

Route of the Red Rock Stage that ran from Red Rock MT. to Salmon ID from 1866 to 1910, a 125 mi. daily trip, year round. The "Mud Coach" was pulled by 6 horses The ranch house to your right was the original stage stop.

”…you will take careful observations of …objects distinguished by such natural marks & characters of a durable kind…”

—President Thomas Jefferson

There is a remarkable view from the crest of Clark's Lookout and it is easy to see why Clark chose this rocky outcrop. Look south to see the Blacktail Deer Range and the Tendoy Mountains; the Sweetwater and Ruby Ranges rise to the east; the Tobacco Root and Highland Mountains are to the north; and the Pioneer Mountains dominate to the west. These mountain ranges, and the valleys that lie between them, have been forming for approximately 20 million years as a result of the Earth's crust pulling apart (see cross section). The sinuous and shallow rivers that developed in these broad, flat valleys presented a time-consuming and demanding physical challenge for the Corps of Discovery. Clark noted in his journal that on August 11th they traveled 14 miles by water for 5 miles in a direct line. On August 12th he wrote:

”…men complain verry much of the emence labour they arte obliged to undergo and wish very much to leave the river. I passify them.”

—William Clark, August 12, 1805

This exposed chunk of limestone originated as shell material that settled to the bottom of a shallow tropical sea, which covered the area about 360 million years ago. Look carefully at the rock and you might find the shells of animals that lived in this ocean. The limestone was heaved upward by movements along faults in the Earth during the process of mountain building. Similar faults have uplifted entire mountain ranges, including the ones you can observe from the top of Clark’s Lookout. The limestone has not been eroded away since it was uplifted and exposed because this rock type resists erosion in the dry climate of southwest Montana. Limestone comparable to that of Clark’s Lookout lies hidden beneath the sand and gravel that fills the Beaverhead Valley (see cross section).

A Geologic Timeline of Clark's Lookout

Phanerozoic Eon

• Cenozoic Era

Present (Clark stands on the exposed rock in August, 1805)

Quaternary Period (about 2 million years ago)

Tertiary Period (about 65 million years ago) (Uplift of the Clark’s Lookout rock begins)

• Mesozoic Era

Cretaceous Period (about 144 million years ago)

Jurassic Period (about 208 million years ago)

Triassic Period (about 245 million years ago) (the first dinosaurs)

• Paleozoic Era

Permian Period (about 286 million years ago)

Pennsylvanian Period (about 320 million years ago)

Mississippian Period (about 360 million years ago) (Formation of the limestone that makes up Clark’s Lookout)

Devonian Period (about 408 million years ago)

Silurian Period (about 438 million years ago)

Ordovician Period (about 505 million years ago)

Cambrian Period (about 545 million years ago)

Proterozoic Eon (about 2500 million years ago)

Archean Eon (about 4500 million years ago) (Earth and other planets formed)

Data compiled by Dr. Robert C. Thomas, Professor of Geology, The University of Montana – Western.

Erected by Montana State Parks and University of Montana Western.

Looking for Clark

As the sun rose over their camp on the morning of the 17th of August 1805, Captain Meriwether Lewis dispatched his interpreter George Drouillard downstream to search for Captain William Clark and the rest of the expedition. Lewis had spent a restless night worried over the fate of Clark and the rest of the party.

During the week before, Lewis and three men went ahead of the slow-moving canoes. They found the Shoshoni camped on a river over the mountains to the west in present-day Idaho. Returning on the evening of the 16th with a small party from the village, they made their camp just below the forks. Expecting to meet Clark, "the chief with red hair," they nervously waited in the predawn light.

As Drouillard prepared to ride, the Shoshoni Chief Cameahwait, concerned for the safety of his people, sent several of his men to accompany Drouillard in his search for Clark. The Shoshoni had been reluctant to follow the strangers in fear that they were being led into a trap. Lewis assured them Clark would be here with trade items. He desperately needed their help, and hoped to procure horses from them in order to continue his journey. His focus now turned to holding their confidence. If they did not find Clark as he had promised, the Shoshoni would leave.

Reunited at Last

Drouillard and the warriors rode less than two miles downstream when they found the men dragging the canoes over a gravel bar. Captain Clark had heard the Shoshoni warriors singing before they came into view. Sacajawea, walking out in front of everyone, recognized the riders as those of her tribe, the Aqaidika, or Salmon Eaters. In her excitement she looked back at Clark and began to dance and suck her fingers indicating in sign language that these were her people.

As Clark, Sacajawea and her husband Charbono (sic) entered camp, Lewis, Camealwait and the rest of their Shoshoni gathered to greet them. From this small waiting party an excited young woman ran out to embrace Sacajawea. Five years earlier two young girls had been captured in a raid. One escaped and was able to return to her people, while the other had been taken to the Mandan villages, where she would become a vital member of the Corps of Discovery.

Today when the wind blows from the west, you can close your eyes and still hear their cries of joy. Best friends reuniting at last.

Erected by Reclamation, University of Montana Western.

In Commemoration of

Sacajawea who guided Lewis and Clark through this the land of her childhood and capture

On August 17th, 1805 she rejoined her tribe near this site. The services she rendered the expedition were invaluable.

This tablet was erected by the

Montana Daughters of the American Revolution 1915

Erected 1915 by Daughters of the American Revolution, Montana.

Launched May 15, 1895, the remains of the F.L. Graves electric dredge boat now lies in Grasshopper Creek.

Erected by Montana State Parks.

In 1804-06, Captains Meriwether Lewis and William Clark led about 40 soldiers and boatmen on an epic journey. President Thomas Jefferson commissioned this “Corps of Discovery” to find a route to the Pacific Ocean through the newly acquired Louisiana Territory. Along the way, they mapped the land, recorded its resources, and contacted its native inhabitants. The landscape has changed since Lewis and Clark explored it: rivers have been dammed, forests cut over, prairies plowed under, and roads built to the horizon. Although remnants of wilderness still exist, imagine this land as Lewis and Clark first saw it two centuries ago

Erected by National Park Service, U.S. Department of the Interior.

At the beginning of the 1800s, the science of Geology still was in its infancy; in fact the word geology in its currently accepted meaning was not used until 1778. Before the mid-1700s, the study of the origins of the earth and its rocks, rivers, and mountains was essentially a philosophical plaything, a part of Natural History or Natural Philosophy. In America, the science of geology was even less known and less developed than in Europe. Lewis had neither formal not practical training in geology, mining, or mineralogy, although he possibly had the opportunity to acquire some knowledge from Jefferson's library. Lewis' second in command, Clark, also had no training or experience in geology. The other members of the expedition were principally backwoodsmen, hunters, or enlisted soldiers. Like their leaders, much of their "understanding" of geology was based on the common knowledge and popular misconception of the time.

The geologic vocabulary of Lewis and Clark reveals much about their understanding of geology. The journal entries name several rock types: chalk, flint, flintstone, freestone, granite, lava, limestone, marble, marl, pumicestone, sandstone, sand rock, slate, slate stone, and slate rock. Lewis and Clark generally used the terms chalk, marl, and sandstone, correctly. They applied the term freestone to any rock that was layered, split, or looked like it could be split easily into layers; generally, for rocks that we now know were sandstone and limestone. Sometimes, however, they used that term for rocks that certainly were granitic, perhaps seeing the slabs that resulted from spheroidal weathering or seeing closely spaced fractures. Lewis and Clark occasionally used the term flint, sometimes correctly, sometimes applying it generically for many silica-rich rocks. They used granite both for any crystalline rock and for any hard rock that was not distinctly bedded even though of sedimentary origin. Generally, when they called a rock limestone. it was limestone, but some limestone that they saw they called granite or shale. They used the term marble in the sense of an ornamental stone rather than as a rock, and lava and pumicestone for the products formed from the burning of coal beds. They used the term slate for shale, argillite, or any other thin-bedded rock that was not sandstone or limestone.

Except for the common metals, the explore's mineral vocabulary was largely apothecary or medical in origin.

Among the mineral terms in their vocabulary we find: alum, arsenic, cobalt, copperas, epsom salt, glauber salts, iron ore, isinglass, lead, lime, marcasite, mercury, niter, pyrite, quartz, salt, saltpeter, salts of tartar, silver, talc, white vitriol, and yellow ocher. Most of the minerals and salts that Lewis and Clark identified using these names were identified incorrectly.

Lewis and Clark (but especially Lewis) often ascribed colors to rocks that probably resulted from conditions of sunlight, shadow, or vegetation rather than to actual color of the rocks themselves. This incorrect description of rock colors has caused confusion regarding the location of certain geographical features. Lewis, for example, on July 19, 1805, wrote: "...this rock is a black grannite below and appears to be of a much lighter colour above and from fragments I take it to be flint of a yellowish brown and light creemcolord yellow...from the singular appearance of this place I called the gates of the rocky mountains ..." Some have argued that historians have misidentified the location of the Gates of the Mountains because the rocks there are neither granite nor black. Yet careful study of Clark's maps and the expedition's original river survey places that observation precisely at the spot that now goes by the name Gates of the Mountains.

Both Lewis and Clark had a good command of geographic terms and used most of them in their current meaning. Lewis also seems to have had a more specialized geologic vocabulary, perhaps derived from books in Jefferson's library. Among the specialized terms he used appear: argillaceous, calcareous, carbonated wood, conchoidal fracture, crystallized, fossil, incrustation, interstice, and strata.

If the geologic descriptions and interpretations that Lewis and Clark make are evaluated with respect to their lack of specialized training, most of their observations can be interpreted satisfactorily Lewis and Clark and the others of the expedition boldly excel is not in their interpretations of geology, but in their observations of it. Their geologic observations were among the finest of the day in America. In addition both men seemed well aware of certain geomorphic processed, especially river mechanics. This knowledge likely did not come from the books available to Lewis as Jefferson's secretary, but from his practical experience and his keen observational ability. Clark had even less chance to learn geology from scientific books of the day, yet his skills as an observer and his understanding of stream processes are consistently demonstrated in his writings.

Most geographic and geologic descriptions in the expedition's journals are interesting in themselves. They become more interesting and useful when the reader knowns what the feature described was or how it relates to the surrounding geography or geology. Below is a short quote for Lewis' journal entry dated Monday 15th, 1805, footnoted with current geological information and descriptions (journal entry as transcribed by Gary E. Moulton, Editor, "Meriwether Lewis and William Clark, The Journals of the Lewis and Clark Expedition." with permission):

"... we have now passed Fort Mountain¹ on our right it appears to be about ten miles distant. this mountain has a singular appearance it is situated in a level plain, it's sides stand nearly at right angles with each other and are about a mile² in extent, these are formed of a yellow clay³ only without the mixture of rock or stone of any size and rise perpendicularly to the hight of 300 feet.⁴ the top appears to be level plain⁵ and from the eminence on which I was yesterday I could see that it was covered with a similar cost of grass⁶ with the plain on which it stands. the surface appears to also to possess a tolerable fertile mole of 2 feet thick. and is to all appearance inaccessible. from it's figure we gave it the name of fort mountain..."

• ---------------------------------------------------------

¹ Square Butte, which rises 22 miles southwest of Great Falls and 10 miles west of Ulm.

² The butte's east and west sides are about 1 ½ miles long and its north and south sides are about ¾ mile each.

³ The most conspicuous part of Square Butte is the nearly horizontal mass of an igneous rock called basalt that form the upper three-fourths (700 feet) of the butte. The basalt is all that remains of a laccolith-a "blister of solidified magma that intruded sedimentary rocks and domed them upwards. This laccolith formed during the Late Cretaceous time when magma from the volcanic center of the Adel Mountains, about 10 miles south of the butte, intruded a near-vertical fracture in sedimentary rocks. As this magma sheet reached the area where Square Butte currently stands, it began to force its way between the horizontal layers of sedimentary rock, bowing the upper layers upward as it continued to flow in. The nearly flat base of the laccolith may then have been more than 2000 feet below ground surface. As the molten material cooled and solidified, vertical cracks (joints) developed in the rock. These joints generally formed six-sided columns which can be seen around much of the rim of the butte. Horizontal layering of the laccolith also can be sen in certain localities. The basalt (Shonkinite) that forms this laccolith is much more resistant to erosion that the sedimentary formations into which it forced its way.

The sedimentary formation in which the laccolith intruded is named the Virgell Sandstone. It was deposited as a coastal sand about 80 million years ago during the Late Cretaceous and is the same formation that produced the White Cliffs of the Missouri about 150 miles to the northeast (the White Cliffs also are noted in Lewis' journals). Originally about 399 feet thick, only about 120 feet of the Virgelle Sandstone remains here; it is found just below the basalt. Erosion has removed the upper 280 feet of this sandstone and all the formations that lay above it. Below the Virgelle Sandstone is the Telegraph Creek Formation; it is about 300 feet thick and is fairly sandy at the top, but grades downward into shale. The base of the butte is composed of the Marias River Shale, named for its exposures near the mouth of the Marias River.

⁴ Square Butte's highest point is at 4797 feet above sea level; the height of the surrounding plains ranges from 3500 to 3700 feet, Thus the summit is more that 1000 feet above the plains-not 300 feet. Lewis' description of the length and shape of Square Butte and the nature of its summit surface shows that he gave the butte more than just a casual glance, but it is hard to explain how he underestimated it height so badly or failed to notice the rock that rings the summit plain. He must have assumed that the material forming Square Butte was the same as that of the smaller, still-unnamed buttes near the falls that he had seen on June 13, 1805 from less than 2 miles away,

⁵ The more nearly level summit plain altitude averages 4650 feet and contains at least 1000 acres (1.6 square miles).

⁶ On this upper plain grow plants specimens that are more indigenous to the pre-settlement plains than those that now grow on the plains that surround the base.

This map provides an overview of the routes and campsites of the Lewis and Clark Expedition in Montana that will enable a general understanding of the fascinating geographical and geological observations recorded in their journals. For a more detailed and comprehensive accounting of campsites or for information about our broad catalog of reports and geologic maps, please contact the Montana Bureau of Mines and Geology.

R.N. Bergantino

Associate Research Hydrologist Montana Bureau of Mines and Geology

This property has been placed on the

National Register of Historic Places by the United States Department of the Interior

William Clark was central to the success of the Corps of Discovery expedition not only during the two years spent crossing the continent but also because he produced maps of the west long after his return.

His three maps of the Western United States were produced from sketches made during the expedition. He completed detailed maps during the winters of 1804 and 1805 in Fort Mandan and between 1805 and 1806 in Fort Clatsop. The third map was finished in St. Louis between 1809 and 1810. Clark had an extraordinary ability to illustrate the landscapes he observed onto a one-dimensional map as well as a natural instinct to determine the course of rivers beyond his sight. Clark's maps accurately showed the west as having multiple mountain ranges, rather than a single range, as was commonly believed at the time.

His brother George Rogers Clark recommended him to Thomas Jefferson after turning down Jefferson's offer to lead the expedition. Jefferson then recruited Meriwether Lewis. Lewis had served under Clark in the military, after which the two men became friends. Lewis offered Clark the opportunity to join the Corps. Clark responded to Lewis accepting the offer.

I will cheerfully join you in an “official Carrector” as mentioned in your letter and partake of the dangers, difficulties and fatigues and I anticipate the honers and rewards of the result of such an enterprise…

—July 18, 1803

An experienced woodsman, military commander and surveyor with an outgoing and even temperament, Clark complemented Lewis’s skills and traits to provide a strong shared leadership of the Corps.

Erected by Montana State Parks.