Horse Pens 40: My favorite bouldering location

I returned Monday morning from a three day trip up to Chattanooga, Tennessee for a bouldering trip to LRC, a.k.a. Stonefort. Unfortunately, we got only one good day in before a large amount of snow fell on the site and made travel up and down the mountain a bit dangerous. So, we packed up and drove to Horse Pens 40, a natural boulder field atop Chandler Mountain in northeast Alabama.

I love HP40, and not just for the climbing. It has a rich human and natural history. HP40 has been inhabited by humans for about 15,000 years. The sandstone rock formations have served  as natural horse corrals and Native American burial sites, among other things. This rock is full of huecos (climber lingo for holes or pockets) and many large slopers (more climber lingo for big, rounded features). Much of the rock has been shaped by water grooves, where water running off the top of a boulder has etched shallow grooves into it. This rock is tough and harsh on the hands. I found it rougher than LRC's boulders.

The setting of HP40 is also very scenic, being located in the woods atop the mountain. I'm not sure what the dominant tree here is, but I did notice many shells that looked similar to the hickory nuts we have back home in Ohio. I also noticed many seed-bearing structures that were spherical in shape with a diameter roughly larger than a quarter. These structures had already released their seeds (the date was early February), which I presume covered the surface of this sphere.

The outstanding science question of this trip is: why is rock "stickier" when it's cold? By sticky, I mean that a climber's hands and shoes are less likely to slip.

Back in action... and optomechanical backaction

I returned to Orlando on the red eye from LA Monday morning and am back in the swing of things (paper writing, data analysis, fixing broken equipment, etc.). I unfortunately had the flu for part of the FiO conference, so I did not attend many talks. A few that I did see and were interesting included FMD1: Near Threshold Optomechanical Backaction Amplifier, FTuZ1: Extracting information from optical fields through spatial
and temporal modulation, and FTuS7: Optically Induced and Directed Manipulation on Surfaces. The abstracts and submissions should be up at http://www.opticsinfobase.org/ within the next month.

FTuS7 was especially interesting. This group out of Oxford used an optically heated metallic substrate to form colloidal crystals from thermophoretically and convectively trapped silica microspheres. They employed standard video microscopy to observe the grain boundaries between two crystals and recorded the annealing time—the amount of time it took for the grain boundary to disappear due to large scale reorientation of the two crystals. The position of the nucleation sites for the crystals were controlled by splitting and directing the laser beam through the microscope objective with a spatial light modulator.

Pretty cool stuff. Fortunately, I got better in time to do some climbing in Yosemite. This time we hit the Five Open Books and I followed on my first Yosemite 5.9, Commitment. The crux on Commitment is ridiculous.