Mark Wilson July 14th, 2010
LOGAN, UTAH–I’m here to spend a few days with my parents who are “summer citizens” on the Utah State University campus. Logan is in the far northeastern corner of Utah near Idaho. Like all of the state, it has fascinating geology. Only California can match Utah for geological diversity and splendor. There is a reason why so many geologists find themselves coming back often to Utah.
This evening we walked to the eastern edge of the USU campus and looked at the Bear River Range a few kilometers away. It is a very complex packet of rocks, part of the Logan-Huntsville Allochthon (an allochthon is a set of Paleozoic rocks pushed out of place by tectonic activity). The East Cache Fault Zone separates the valley which contains Logan from the mountains. Some geologists believe it represents the boundary between the Basin and Range Province to the west and the Middle Rocky Mountains Province to the east. In the image below you can see that the zone is primarily a set of normal faults. In the Logan area it shows movement during the Holocene, and it is still active today.
Tomorrow we explore Logan Canyon, which cuts perpendicularly through the Bear River Range, and look at the exposed carbonate rocks in detail. I can smell the fossils from here.