Alberton in Mineral County, Montana — The American West (Mountains)
Glacial Lake Missoula
and Transportation Along the Clark Fork
• Glacial Lake Missoula was first created about 15,000 years ago when an enormous glacier
• The lake was comparable to the size of Lake Erie or Lake Ontario and covered much of western Montana.
• Glacial Lake Missoula filled and emptied on a regular basis over a period of 2,000 years. Catastrophic floods occurred when the ice dam broke, leaving scars on the landscape in eastern Washington.
• John Mullan built the first engineered road in Montana between 1859 and 1862.
• Count how many times you can see old shoreline on the mountainsides along Interstate 90.
In 1860, 150 men under the command of Lieutenant John Mullan carved a wagon road through the colorful Precambrian mudstones on the mountainside north of here. The road took six weeks to construct and required the use of explosives to blast a route through the rocks. Called the Point of Rocks Segment of the Mullan Road, the road still traces its way across the mountainside above here. In 1908, the Chicago, Milwaukee, St. Paul & Pacific (Milwaukee Road) Railroad constructed its transcontinental line through the Clark Fork canyon enroute to Seattle. The railroad also excavated tons of rock to cut its way through these mountains to St. Paul Pass. The old railroad grade, later known as the Route of the Hiawatha for the celebrated passenger train that once used the line, is still evident along the north side of Interstate 90. In 1914, the Yellowstone Trail, blazed by distinctive chrome yellow signs with black arrows, passed through this canyon. The trail became U.S. Highway 10 in 1926. Interstate 90 bypassed it here in 1963.
Erected by Montana Department of Transportation.
Location. 47° 1.252′ N, 114° 31.218′ W. Marker is in Alberton, Montana, in Mineral County. Marker is on Interstate 90 at milepost 73, on the right when traveling west. Touch for map. Marker is in this post office area: Alberton MT 59820, United States of America.
Other nearby markers. At least 4 other markers are within 7 miles of this marker, measured as the crow flies. A Wonderful Piece of Engineering: The Big Side Cut (within shouting distance of this marker); The Natural Pier Bridge (approx. 0.8 miles away); Flying High Across the Big Sky (approx. 1.2 miles away); The Ninemile Remount Depot (approx. 6.6 miles away).
More about this marker. This marker is located at the Alberton Rest Area, Westbound on Interstate 90 MP73
Categories. • Natural Features • Paleontology • Railroads & Streetcars • Roads & Vehicles •
Credits. This page was last revised on September 7, 2018. This page originally submitted on September 7, 2018, by Barry Swackhamer of San Jose, California. This page has been viewed 43 times since then. Photos: 1, 2. submitted on September 7, 2018, by Barry Swackhamer of San Jose, California.