First summit of the year

It really is a testament to the amount of snow and the cold spring that our first summit (and it really wasn't a real mountain) was on July 1st. Even now, many trailheads are not open and if they are the amounts of snow, especially in the sub-alpine forest is still pretty deep. We had tried other peaks earlier and were unsuccessful on everyone. So Twin Peaks right outside of Ouray was our first summit of 2011.

The summit rock is part of the San Juan formation or just the San Juan Tuff a volcanic-clastic sedimentary rock. Within this impressively thick formation (3000 feet in places) , you can identify breccia clasts from long ago pyroclastic flows and thick welded tuff segments resulting from falling ash. A cool place!

The "little sister" right before the last big climb. Even without zooming in you can see the brecciated surface.

There is still a bit of snow in the high country
A long way down to the City of Ouray CO. This was a fun 3000 foot climb.
An close up showing the volcanic-clasts within the matrix. Unfortunately there is quite a bit of biology hiding the rock details.

The only geologist on an archeology trip

Way back in graduate school my emphasis was on the glacial history of the Colorado Rocky Mountains. At the time, I loved the alpine environments, the cold temperatures and the climbing associated with glaciers. However, as I have grown older I have found that I enjoy the warmer climate of the desert southwest. Please don't get me wrong, I still spend time in an alpine environment, but the desert places have captured a big part of me.

While exploring the canyons found in the southwest I have changed my geology interests from glacial episodes of the Quaternary to the ergs of the Mesozoic. With more and more time spent in the canyons, I have found a strong interest in the previous occupants of the canyon country. You can only look through so many ruins and see so many rock art panels before you are just driven to know more.

So, a few weeks ago I joined a group of both professional and amateur archaeologists on a float down the San Juan river in SE Utah. What fun! What great examples of rock art. And, I was able to explain how some of the geology happened to be. The story in the rocks actually started 350 million years ago...not just 1100 years ago

Chert nodules

iron concretions. Many of my fellow explorers were not ready for a little chemistry lesson at river side to explain the origin of either the chert or the concretions.
The rock art was tremendous

The Mexican Hat. What a great example of the more resistant cap rock
The Raplee anticline

Where did the Wingate go?

If you have read this blog for any amount of time, you have already gathered that my favorite formation on the Colorado Plateau is the Wingate sandstone. In fact, the cover photo of the blog is of the Wingate sandstone along the Green River. It is a late Triassic- Jurassic aeolian sandstone. The grains are very uniformed in size making fantastic conchoidal fractures when blocks fall from the cliff face. Making a very nice cap rock on top of the Wingate is the Kayenta formation. The Kayenta, an early Jurassic siltstone-sandstone showing evidence of mid energy stream action is cemented very well and acts as an excellent cap rock. The top most component of this group (the Glen Canyon Group) is the Navajo Sandstone. This sandstone is another Jurassic aeolian sandstone that hints at being one of the largest sand islands ever seen on planet earth.

But...back to the missing Wingate.

Most of my play area is in Southeast Utah along the Colorado and Green Rivers. This past month we have spent some serious time in South central Utah in the Paria drainage. Here we see the familiar Glen Canyon Group wit the navajo sandstone along the horizon, the Kayenta formation directly below but instead of another aeolian sandstone there the Moenave Formation with reddish siltstone and pinkish sandstone showing clear evidence of water deposition. What a difference from the windblown Wingate.

The story in the rocks suggests that perhaps, in the early Jurassic we would have been in a desert resort area with ponds and streams with a large desert just to the east. A paleo-Palm Springs?

Canyon cliffs of Navajo sandstone with the Kayenta formation making the canyon bottom

Canyon walls of Wingate sandstone
And 100 miles to the west... the high white cliffs of Navajo sandstone, the reddish ledges of the Kayenta formation and the reddish-pink slope forming Moenave formation near the bottom.

high water

Last weekend while exploring different parts of the Uncompahgre Plateau we came across an unfortunate place to leave a truck. With the recent warm weather (and the extra long cool spring) the rivers are coming up high and fast.

Its not only the rafters that need to be careful around rivers.

History lesson turns to a chemistry lesson

A few weeks ago I described a snowshoe history field trip of the Red Mountain Mining District. This area took out millions of dollars of metals in the late 19th century and early 20th century. Unfortunately the profits are long gone and we are left with the clean up. There was lots of evidence of iron in most every mine in the area. Obviously, the RED in Red Mountain is due to iron mineralization in the rocks.

What hard rock mining did was increase the air and water exposure to the iron pyrite found naturally in the geology of Red Mountain Pass. Iron pyrite (FeS2) reacts with the water and oxygen to form sulfate (SO4). which combines readily with water to form sulfuric acid and ferrous iron.

FeS₂ + O₂ + H₂O = Fe²⁺ + SO₄^2- + H⁺

The ferrous iron reacts with the air and water to create ferric iron. The ferrous ions are soluble in water while the ferric ions are not. The ferric ions precipitate out of the water coating the entire substrate with an almost impervious layer of iron. No matter the water chemistry, this iron pavement alone signals the end for any biology in the water, there is no place for macroinvertebrates to live, no place for aquatic plants to take hold. The food chain dies at the lowest trophic levels.

Fe²⁺ + O₂ + H⁺ = Fe³⁺ + H₂O

However, the water chemistry is not normal. Most biology needs a near neutral pH to live. The sulfate ions reacting with water results in the formation of sulfuric acid, lowering the pH to extreme acidic conditions. I have measured the pH of alpine creeks down to 2.0.

FeS₂ + Fe³⁺ + H₂O = Fe²⁺+ SO₄^2- + H⁺

Part of trying to fix the Uncompaghre water shed is to determine how bad was the water prior to mining. At the time, the miners did not do any environmental impact studies before they started digging. The best we can do are some anecdotal comments about catching fish just outside the mining camps- an impossibility today. It is obvious that there was natural mineralization present before the advent of mining. So, how much can be cleaned up today?

Do we have the will to clean up seriously degraded waterways way up in the headwaters?

Red Mountain #1

Looking for red rocks next to the channelized and embedded Red Mountain Creek
Part of an old tailings slurry pipeline. The miners used wooden flumes because the metal corroded to quickly with the acidic water.
Red Mountain Creek in the winter. The yellow water stands out nicely against the white snow.

feng shui on the trail AW 33

This month, John in the Taconic Mountains has asked about how we incorporate geology into our homes. I was thinking about some landscaping we had done in the backyard or about the fireplace in Ed Abby's old home in Moab UT where the rocks represent the stratigraphic column of the Canyonlands. BUT

I didn't have any pictures. I know that this isn't exactly what John had in mind, but it sure beats the shelf with my "prettiest" hand samples.

Last week I was visiting Zion National Park and hiked up the West Rim Trail past the infamous Angels Landing. While walking up "Wally's Wiggles" we saw this fantastic example of a Navajo sandstone iron concretion used in the retaining wall. Whoever was trail crew leader had a great eye for aesthetics and incorporated some fun geology in the trail.

Looking way down at Wally's Wiggles. Click the image for a larger version.

the concretion in the wall
up close

A history lesson

A few weeks ago I attended a ski/snow shoe tour of the Red Mountain Mining District courtesy of the Ouray Historical Society and the Uncompahgre River Project. The area I took the most pictures was the picturesque Yankee Girl mine.

The Yankee Girl was discovered in 1881 and by the time most mining had ceased in 1896 over 3 million dollars of gold, silver and lead had been brought to market (while leaving tons of debris on he ground near the mine). The Yankee Girl. like most mines in the district took advantage of several volcanic breccia chimneys, a result of the creation of the Silverton caldera. The most productive ore seems to be associated with the quartz porphyry found in the chimneys. Lead and zinc ore paid he bills, the silver provided the profit and the little gold that was found provided the headlines.

lunch at the Guston mine

The Yankee Girl headframe
The Yankee Girl up close. The main mine shaft dropped over 1000 feet from this point.