Sunday, May 31, 2009

summer reads

The summer season has been busy already. I had 5 fantastic days doing geology through Labyrinth Canyon with a Denver museum. There were 4 of us geologists all with different specialities and a boat load of interested lay people with us. Great fun! We are now getting ready to visit Yosemite and some places in Nevada (I have been studying Silver Fox's posts to get a lost together). The editors of my latest writing assignment have been busy so if I am not packing I am fixing edits.


I am also getting a list of geology books together for the back of the truck. I am re-reading McPhee's Basin and Range and Assembling California for our next trip.

Let's get a list together of great geology books that we can all read this summer!

Sunday, May 17, 2009

Playing in the Entrada

Way back in the mid Jurassic, about 150 million years ago the Colorado plateau region of Utah was in the middle of a huge, Sahara-esque desert. Sediment from the rising mountains in Nevada blew across western Utah and was deposited in huge dunes in what we now call the slick rock member of the Entrada formation.  

The Entrada formation is divided into three members, the middle member, called the slick rock member gets most of the press. The oldest member is named after the now burned-to-a-crisp Dewey Bridge. It consists of siltstone and is a holdover from the underlaying Carmel      formation. The oldest portion, called the Moab 
member slowly grades into the Summerville formation. 

But it's the middle member we all go to Arches NP to see. These last two weekends were no exception. The first few images show the landscape near the Herdina park section in the national park. We wandered around this sandstone island finding balanced rocks, arches and alcoves.

Eye of the Whale arch

This past weekend was looking at the arches in the Black Ridge Wilderness. The trail starts at the river and climbs, sometimes steeply as evidenced by the BLM trail marker.

At trails end is the second largest concentration of arches in the US. 

Tuesday, May 5, 2009

Dirty Snow

I spent the other day checking out the early May snowpack on Red Mountain Pass here in the San Juan Mountains...some one had to do it!  Our winter produced an above average snowpack (just barely) which bodes well for the summer wildflowers and low elevation irrigation, but it is melting rapidly. This winter also produced three strong wind events that blew red dust in from Utah. The higher elevations were covered in red snow while the lower elevations saw muddy rain. The dust on the surface of the snow impacts the albedo and less solar energy is reflected back into the atmosphere. In addition, the desert dust that is mixed throughout the snowpack has a different specific heat than the snow. As the spring temperatures warm, these dirt and dust particles heat up faster and in turn melt the snow faster than historical records would suggest. Snowpack that once would last into July is now melting out in June. Rivers which should run high into the early summer peak out in May.

The last image shows the current state of the Gunnison basin snowpack. The smooth line represents the 30 year average. Look at the slope of the last few years of snow melt. I think there is a message here.

dirty snow at 11,000 feet

harder to see, but the snow fields are covered in dirt