Along the ICE AGE FLOODS
NATIONAL GEOLOGIC TRAIL

Glacial Lobe Dam at Green Monarch Ridge View Point Ice Age Floods National Geologic Trail  As the Purcell Trench ice lobe of the Cordilleran Ice Sheet advanced south from Canada, it was stopped by the Green Monarch Ridge, building an ice dam 4,000 feet (1219 m) tall and nearly 40 miles (64 km) wide that blocked the Clark Fork river, thus filling glacial Lake Missoula. View the Green Monarch Ridge and the Purcell Trench from a large pullout on Idaho State Route 200, about one mile (1.6 km) west of Hope, Idaho and 15 miles (24 km) east of Sandpoint, Idaho. Quick Facts Location: Idaho State Route 200, about one mile west of Hope, Idaho and 15 miles  east of Sandpoint, Idaho.

Ice Age Floods National Geologic Trail 12,000 to 17,000 years ago a 4000′ tall ice dam blocked the path of the Clark Fork River creating glacial Lake Missoula. At the end of the last ice age this ice dam failed, releasing more water than is held in modern day Lake Ontario and Lake Erie combined. 600 cubic miles of water rushed through this area and down Lake Pend Oreille destined for the Pacific Ocrean.One of the most intriguing questions about the catastrophic flooding is how the ice dam failed. Various mechanisms for glacial outburst floods have been proposed: Ice erosion by overflow water, subglacial failure by flotation, deformation of ice by water pressure, and erosion of subglacial tunnels by flowing water. One model suggests a self-dumping phenomenon. In this mechanism, floodwaters are released when the lake level reaches nine-tenths the height of the ice. At this depth the ice becomes buoyant, subglacial tunnels form and enlarge, and drainage occurs until hydrostatic pressure is decreased and the ice again seals the lake. The self-emptying model is used to explain the numerous cycles in the rhythmite deposits and to interpret each cycle as a separate flood. Even so, only the total collapse of the ice dam can explain the largest of the catastrophic foods. Sub-glacial tunneling and enlargement due to thermal erosion progressing to collapse have also been proposed, as well as catastrophic failure due to water pressure. All are dependent on the configuration of the ice dam and structure of the ice. Quick Facts Location:Clark Fork, Idaho

Museum of North Idaho IceAgeFloods National GeologicTrail “The Museum of North Idaho collects, preserves and interprets the history of the Coeur d’Alene Region. to foster appreciation of the area’s heritage.” In the 1960s, the North Idaho Hoo Hoo Club, an organization of loggers, lumbermen and foresters, first entertained the idea of establishing a museum. They incorporated on May 1, 1968 for a museum focusing on the history of the Coeur d’Alene Region (Kootenai, Benewah and part of Shoshone counties). Through the efforts of volunteers and community support, the Museum opened its doors on the North Idaho College campus on July 28, 1973. In 1979, they remodeled a City-owned building and relocated to its current location. Quick Facts Location: 115 Northwest Blvd, Coeur d’Alene, ID 83814Phone: (208) 664-3448 The Museum is open Tuesday to Saturday from 11 am – 5 pm.