Looking southwest across the middle Pahsimeroi Valley at the Lost River Range

Notes on the Pahsimeroi Basin


When WC moved to Idaho a few years ago, WC knew it was a state that has an extensive basin and range province. “Basin and range,” for non-geologists, is a patter of alternating steep mountains and broad, mostly flat valleys. The mountains and valleys all extend northwesterly, mostly parallel, and are major geoform of the…

This diagram shows the Georgetown terrane, in green, joining Australia around 1.6 billion years ago during the formation of the supercontinent Nuna. Credit: Geology, https://doi.org/10.1130/G39980.

Back When Australia Was Part of North America


Long-time readers of this blog understand that the continental plates are in a very, very slow dance around a earth-sized, spherical skating rink. They collide, separate, collide, and separate again in a supercontinent cycle that’s been going on for perhaps 3 billion years. Collisions among the continental plates create supercontinents; the supercontinents rift apart. The…

Blue-gray areas were flooded during one or more of the Missoula Floods

One More Glacial Lake and Megafloods


Glacial Lake Ahtna dominated Alaska’s southcentral region during the Ice Age. Utah’s massive Lake Bonneville triggered the Bonneville Flood. But both Lake Ahtna and Lake Bonneville, stupdendous flood events themselves, were mere pikeminnows in comparison to the┬ásturgeon┬áthat was Glacial Lake Missoula, which was not only a bigger flood event but happened as many as 80…

Leslie Gulch, Owhyee Mountains, Oregon

Geology 101: Leslie Gulch


In addition to driving on stupidly dangerous goat paths, WC spent the weekend in the deeply dissected volcanic rock of the Mahogany Mountain Caldera, in the southeastern corner of Oregon, near the Idaho state line.. Leslie Gulch is actually inside that 15.5 million year old caldera, which is some 15 kilometers wide and 20 kilometers…

Fisherman Road descends at an average 17% grade on a road chiseled into volcanic tuff and cobbles

WC Survived Fisherman Road


On a map, it looks like a nice way to get from Succor Creek Road over to the Owhyee Reservoir in southeastern Oregon. Even on Google Earth it looks pretty straightforward. It’s not. Don’t drive Fisherman Road. Maybe it was the August 2016 Cherry Road Wildfire, which burnt much of the area that Fisherman Road…

Arrowrock Spillway, looking south, Boise River

Some Notes on Arrowrock Dam


Arrowrock Dam is one of three major dams along the course of the Boise River. It’s the oldest of the three, completed in 1915. At 348 feet tall, Arrowrock was the highest dam in the world at the time. It’s primary purpose is irrigation; it holds the winter’s rain and snowmelt so that water is…