Along the ICE AGE FLOODS
NATIONAL GEOLOGIC TRAIL

Green Monarch Ridge Ice Age Floods National Geologic Trail THIS IS WHERE IT ALL BEGAN! The Green Monarch Ridge viewpoint, just south of the Hope Fault, is positioned along the edge of the Purcell Trench Ice Lobe. Here it was responsible for damming the mouth of the Clark Fork drainage basin. This damming effect resulted in the formation of Glacial Lake Missoula, the source of the waters for much of  the PNW Pleistocene Ice Age Floods. The Purcell Trench Ice Lobe originated in Canada and flowed south into Idaho, guided by the structural control of the Purcell Trench. Following the path of least resistance into the basin now occupied by Lake Pend Oreille, it was impeded by the Green Monarch Ridge, located approximately 10 miles south of this viewpoint. Grinding and scraping, the Purcell Trench Ice Lobe backed up behind the Green Monarch Ridge, eventually building an ice plug up to 4,000 feet thick, and scouring out the deepest parts of Lake Pend Oreille. The Purcell Trench Ice Lobe divided into four sub-lobes: one went approximately west (US Highway 2), two went south (US Highway 95 and Lake Pend Oreille) and one went east (SR 200). All four sub-lobes contributed to blocking the Clark Fork drainageQuick Facts MANAGED BY:US Forest Service – Idaho Panhandle National Forest

Lake Pend Oreille Ice Age Floods National Geologic Trail  The Purcell Lobe of the Cordilleran Ice Sheet repeatedly formed a 2000′ tall ice dam in this area, which backed up Glacial Lake Missoula and eventually burst catastrophically, releasing Ice Age Floods as often as about every ~10-60 years. Lake Pend Oreille is the largest lake in Idaho. The lake level is 2062 ft above sea level, with the surrounding terrain as high as 6002 ft. With a maximum depth of 1150 ft, this lake is the 5th deepest in the US. The location of the lake is probably related to an old river valley controlled by faults. The Lake Pend Oreille basin was carved by the repeated advances of Pleistocene ice and scoured by Ice Age Floods. With the waning of flood waters, the basin was filled with glacial out-wash and flood deposits. The lake is dammed at the south end by thick glacial and flood deposits that mark the beginning of the “Outburst Deposits”Quick Facts MANAGED BY:US Forest Service

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.