Thursday, March 28, 2013

Joshua Tree boulder factory

Spent some time in Joshua Tree last week. It has been a long time since I have played in so much granite. In fact it was way back in grad school and we had a professor who always brought the freshman students up to his idea of a "boulder factory" We would spend a little time discussing chemical weathering and then let the students climb around a little bit to experience the sharp quartz minerals left behind.

This was the same thing...only I was the one climbing around. You can clearly see how the once monolithic rock has jointed to make very regular blocks with the resulting acidic water rounding the blocks into spheres. In some cases, you would swear these were very large river rocks eroded down by the movement of water.

 Eroded monoliths with quartz intrusions. These intrusions are harder than the surrounding country rock. In some cases the intrusions were vertical making a quartz wall.
Very spherical boulders. These boulders were once part of a larger monolith similar to the image above.   A series of joints, both vertical and horizontal made regular shaped cubes of granite. Acidic water running through the cracks chemically eroded the feldspars into clay minerals that have since been flushed out leaving behind very smooth spherical boulders.

Friday, March 15, 2013

Did you see it?

4 days camping in the desert
4 days with great open views to the west
4 days with clouds in the west right at sun set and lasting most of the night

Comet Pans STARR borrowed from the web page

Sunday, March 10, 2013

Where is all the snow?

Anyone who has looked through my past blog posts have seen my fascination with our snow pack, whether how big a year we are having or how low a year we are having or about its ability to slide.

This year, like last year is all about how little we have. The graph below, courtesy of the NRCS, shows  the snow totals for the Gunnison River drainage in Western Colorado. The line in the middle is average. The dark line that ends suddenly is this year. Not only are we below average, but we are below last year, a bad year. Note how the slope of the two lines are almost parallel. This suggests that the winter storms are in line with normal. But, look at when we started accumulating snow. The new snow year started last October 1. It took until mid December before any appreciable snow covered the ground. Look at last years graph. It was about this time last year when the snow started to melt. Way ahead of schedule. 

I know that two years do not make a trend. I hope that the next two years will be as high as these years are low, just look at two years ago with a record breaking snowfall. But looking at these past two years with everything else happening around the planet, I wonder if we are starting to see the new normal. Time will tell.