Near Glendive in Dawson County, Montana — The American West (Mountains)
The Red-Capped Hills of Eastern Montana
Before a coal bed can ignite and burn it must be dry and exposed to air. Streams and flash floods erode the hills
Scientists have determined that coal has been burning in eastern Montana for at least four million years, but each burning coal bed eventually extinguishes naturally. As the fire burns into the hill, the overlying rock breaks up and collapses, this allows air deeper into the hill and keeps the coal burning underground. Eventually, too much overlying rock collapses to allow air to enter, and the fire goes out.
(Side-bar at the center:)
• The ceramic-like cylinder rock produced from welded shale is called porcellanite. Similar to pottery, it has sharp edges when broken. For thousands of years, Native Americans made tools from it, such as hide scrapers, knives, and arrowheads.
• The open spaces within beds of clinker make the layers permeable to water. The backed character of the rocks make the rocks less soluble than typical coal of sandstone beds. Therefore, clinker beds are important in the production of less mineralized ground water in southeastern and far eastern Montana.
• The Fort Union Formation is named for Fort Union, an American Fur Company trading
• Read the description about red clinker caps. How many can you spot around you? What about while you are driving?
Erected by Montana Department of Transportation.
Topics. This historical marker is listed in this topic list: Natural Features.
Location. 46° 53.919′ N, 105° 1.163′ W. Marker is near Glendive, Montana, in Dawson County. Marker can be reached from Bad Route Road (Road 235) near Interstate 94, on the left when traveling south. The marker is located in the Bad Route Rest Area. Touch for map. Marker is in this post office area: Glendive MT 59330, United States of America. Touch for directions.
Other nearby markers. At least 1 other marker is within walking distance of this marker. The Yellowstone River (within shouting distance of this marker).
Credits. This page was last revised on January 1, 2021. It was originally submitted on January 1, 2021, by Barry Swackhamer of Brentwood, California. This page has been viewed 44 times since then. Photos: 1, 2, 3. submitted on January 1, 2021, by Barry Swackhamer of Brentwood, California.