The Rocky Mountain Trench

On the High Plains and into the Canadian prairie, the Terrain View of the map has, with notable exceptions, been mostly monotonous. Not so now. I have been watching the terrain ahead as Dee and Cal approach the Northern Rockies, and for a few days now I have noticed a feature that seems highly unusual, a deep valley in a perfectly straight line for hundreds of miles, the orientation of which is an almost uniform 150/330 degree geographic north vector. Today I discovered that this is the Rocky Mountain Trench, primarily the result of faulting (with minimal glacial carving). What you see in the image above is the northern half of the Trench, beginning at the Yukon/B.C. border. It continues at just a slightly different angle to the southeast all the way to Montana.

For orientation, Fort Nelson is in middle of the upper right quadrant (at the confluence of three rivers). The town of Watson Lake would be at the top edge (or barely above it) and toward the left. Prince George would be just off the bottom edge and toward the right. The large lake in the middle of the Trench is Lake Williston on the Peace River. To the northwest, the Tintina Trench continues on through the Yukon to Alaska.

The mountains east of the Trench are the Rocky Mountains, but to the west of it are the Cassiar Mountains in the north and the Omineca Mountains a little further south. We will check out the Trench again when the trikers come back through it a little further south on their way home.