Thursday, February 14, 2013

Loving Life In The Beaver Dam Mountains

It’s never too late to catch up, is it? And if there is anyone who should know this, that anyone would be me. It’s been a month since my last post! It would be no surprise if people thought I’d fallen off the edge of some cliff. 

Hiking my favorite mountains

But I’m still here. Sadly, travels to far–off exotic locations have not been on my winter agenda. It appears that “lazy slug” might better describe my current travel and writing condition. 

The most exotic trip I’ve been on lately has been a hike into the nearby Beaver Dam Mountains. I enjoy spending time in these mountains of extreme southwestern Utah, though. I guess this post is my valentine to a spectacular place. 

Cambrian rocks lift skyward in limb of anticline; hikers in lower right lunch at wide spot in jeep track

I’ve written a post or two about the Beaver Dams and what I’ve done with the time I’ve spent there. Check them out here and here. The area is unique in southwestern Utah in that, in an area of around five square miles, it is the only place where you find nearly two–billion–year–old metamorphic crystalline basement rocks, similar to those found in the inner gorge of Grand Canyon. 

Beaver Dam Mountains

During the winter I lead hikes into these mountains west of St. George, to show folks that there is more to southern Utah than just Navajo Sandstone and Zion National Park. The twenty hike participants who showed up on this most recent February morning were a cheerful lot, at first standing in the freezing shade of a massive roadcut west of Utah Hill on old highway 91, then listening politely as I stopped every five yards and rattled on about garnets and sillimanite and gneisses and schists. They were interested in learning about the geology of the area and I love showing them what’s here. Many had driven this highway time and time again, this back road to Mesquite and Las Vegas, blithely unaware of the extraordinary rocks they were zooming past. 

Checking out the metamorphic rocks

Somewhere around two billion years ago this corner of today’s Mojave Desert was on the periphery of an ancient North America continent. Now it’s the western edge of the Colorado Plateau, a landscape transitioning into the Great Basin. 

Seams of white igneous intrusions pepper the Beaver Dams

Shearing textures seen in broken fragments of rusty red garnets and thready strands of white sillimanite allude to a nearly two billion year history of tectonic collisions and continental rifting, basalt flows and magmatic intrusions, subduction of ancient landmasses and uplift of massive mountain ranges, and the opening up and closing of ancient sea beds. In their own good time, each event has become a fascinating chapter in the geological saga of the Beaver Dam Mountains. 

 Highly sheared garnets are a product of immense forces

Rocks and minerals that were once found at depths of up to 25 miles or more and subjected to pressures of some 188,545 pounds per square inch are now exposed on the surface. Garnet and sillimanite are common in metamorphic rocks, especially mica–schists, and sillimanite in particular is a well-established indicator of pressure–temperature conditions.

Thready strands of white sillimanite tell a story

Depending on whose gps you believe (I think at least five people carried one and they all read something different) our hike was around 5.5 miles, first on an old jeep track and then up and across a ridge line where we stopped for lunch.

Rock lovers all!

Lunch with a view

People come from every corner of the world to experience the natural beauty of southern Utah. I consider myself lucky to live here. With all this breathtaking geology surrounding me I could not hope to see it all in a single lifetime, but I’m doing the best that I can and loving every minute of it.


  1. Welcome Back Home ............

  2. Nina! I just followed the link you posted on facebook and found the most delightful blog.... I hope you are having a good winter! -Eric

    1. Hi Eric - Glad you are now Watching For Rocks and I hope you are having a fine winter also.