Tuesday, February 2, 2010

Road to Jarbidge: Jarbidge Mountains

About 20 minutes west from Salmon Falls Dam, depending on how fast you drive or how many photo stops you make (~25 km or 15 miles), the Jarbidge Mountains come in sight across the volcanic plain. This view is looking southwest to SSW toward the mountains from the 3 Creek–Jarbidge Road. The view is quite similar to the picture in this Wikipedia link, although they incorrectly state that their view is to the northwest.
A closer shot from the same location reveals that a the southern end of the volcanic plain is tilting to the north, right at the junction of the Basin and Range (Jarbidge Mountains) and the Owyhee Plateau—a volcanic plain elevated above the Snake River Plain (SRP), and an area where the track of the Yellowstone hot spot went through about 8 to 14 million years ago. You can also see at least three glacial cirques from this angle, along with Matterhorn, the highest peak in the range. The Matterhorn, third peak from the left, may not be a proper glacial horn, as I can only identify two cirques that have helped shape it.
Now—after 40 to 45 minutes, 60 km or 37 miles—we've come to the last leg of the Jarbidge Road before it drops into the East Fork of the Jarbidge River. We're looking almost due south at the Jarbidge Mountains, behind the northward tilting volcanic plain that looks as though it's been pushed upward by the mountains. Instead, though, the tilting may be from downwarping related to development of the Snake River Plain, although most references discuss downwarping of the eastern SRP, for example here and here, rather than downwarping of the west-central portion of the SRP.
This is the part that fascinated me. I noticed this gap in the tilted plain as I got closer and closer to the downgrade into the East Fork of the Jarbidge River.
The gap is a canyon, or set of canyons, carved into the plain by the East Fork of the Jarbidge River and one of its tributaries, God's Pocket Creek.
The mountain one sees through the gap is called God's Pocket Peak.

Some Links and References:
Beranek, L.P., Link, P.K., Fanning, C.M., 2006, Miocene to Holocene Landscape Evolution of the Western Snake River Plain Region, Idaho: Using the SHRIMP detrital zircon provenance record to track eastward migration of the Yellowstone Hotspot. Geological Society of America Bulletin, September/October 2006, p. 1027-1050.

Hughes, Scott, SRP-Yellowstone Volcanism: Digital Geology of Idaho, Idaho University.

Link, Paul, Neogene Snake River Plain-Yellowstone Volcanic Province: Digital Geology of Idaho, Idaho University.

USGS, Description: Idaho Volcanoes and Volcanics: USGS/Cascades Volcano Observatory, Vancouver, Washington, webpage dated 01/22/03.

Snake River Plain: Digital Atlas of Idaho, Idaho Museum of Natural History.

Southern Idaho Topographic Development: Digital Atlas of Idaho, Idaho Museum of Natural History.

Related Post:
Road to Jarbidge: Salmon Falls Dam


Gaelyn said...

What a gorgeous place to take a ride. Love those mountains, but the gap looks really out of place somehow.

Amanda@Lady Scientist said...

Looks beautiful. And I must admit that the little gap shocked me at first! I wasn't expecting it to be a canyon.

Silver Fox said...

I love the gap - it shows erosion at work, and the tilted, eroded plain made me think of peneplains. One surprising thing about the mountain beyond the gap is that it's 3104-m or 10,185-ft high - not quite as high as the 3304-m, 10,838-ft Matterhorn.