Purcell Trench, Northern Idaho
N 47° 44.356 W 117° 02.010
11T E 497488 N 5287322
Quick Description: This wayside has a sign provided by the Idaho State Historical Society that explains the Purcell Trench.
Location: Idaho, United States
Date Posted: 10/10/2010 12:55:59 PM
Waymark Code: WM9XBT
The sign reads:
A long, glaciated valley, extending from British Columbia this far into Idaho, brought part of a Contenental ice sheet past here thousands of years ago. Rocks and boulders transported here by glacial ice backed up Lake Coeur d'Alene. Then a gradually warming climate let an outlet from Lake Pend d' Oreille discharge past here-sometimes with catastrophic results. As ice receded, Kootnai River also flowed past here before lower channels in British Columbia no longer were blocked by a glacial barrier. In those days, this was Columbia River's main channel.
For additional information about the heritage of Idaho, access the Idaho State Historical Society Website at www.idahohistory.net"
There is also a great deal of information about the Purcell Trench and how it is associated with the Missoula flood, at this website: (visit link