Armchair Adventures

Big Jacks Creek, Idaho

The gently sloping sage covered Owyhee Uplands are located in a very remote region two hours south of Boise.  They have a geologic history that was much more violent than their sublime appearance suggests. The uplands hide a number of dramatic canyons including this deeply eroded cleft formed by Jacks Creek. These canyons provide a window into layers of rock that are evidence of the area’s ancient volcanic activity. As the North American Tectonic Plate moved westward, the stationary Yellowstone Hotspot created a series of giant calderas beginning in eastern OR and NV.  Currently Yellowstone National Park moved sits over this thin area of the earths crust. The hotspot was under the Jacks Creek area around 12 million years ago.  Periods of repeated volcanism during this time deposited the layers of red-brown ryolite rock visible on the canyon walls. Softer layers of unconsolidated ash make up the vegetated layers between the harder ryolite. The unique chemical composition of eruptions from this area known as the Bruneau-Jarbidge volcanic field have been traced to ash deposits that caused the deaths of animals and preserved their fossilized remains more than 1,000 miles east in Nebraska.  

Big Jacks Creek is a far quieter place in the present. The canyon and surrounding uplands conserve a rich array of great basin plant and animal communities. California bighorn sheep seek refuge from predators by navigating the steep canyon cliffs while redband trout find cool shade from the intense desert sun in narrow willow-lined streambed.