Imagine a wall of broken black glass and each boulder and outcrop having edges sharper than then sharpest steel scalpel. A single slip on the edge of a boulder and catastrophe! As I climbed down I carefully placed my foot and then tested it for movement, before releasing my handhold and looking for another. Slipping, my calf grazed a boulder but it was a pumice block, I had been lucky. Why had I ever climbed up! We still had quite a bit to do on our list of musts. One was to visit Obsidian Dome and another was to climb Lembert Dome in Yosemite National park. Having to do some grocery shopping we went to Mammoth Lakes and then returned home for lunch before driving to Obsidian Dome. Now Obsidian Dome is an upwelling of lava that quickly cooled and turned into glass before crystals could form. It formed a black glass with visible flow lines of pumice, where the lava had frothed as gasses had been released. Looking at the black spires I saw an easy way up, and down, and so I started up the talus of huge blocks of obsidian interspersed with pumice. As I climbed, scrambled really, I looked back and saw Renita wisely walking along the base of the cliff. Stopping often I hit some of the boulders with my hammer and they were so solid that my hammer simply bounced off the solid glass! Reaching the top I saw that it was covered with spires of glass and for the first time decided that climbing them would be less then wise. There was beautiful volcanic glass all around me but picking some up I realized that I didn't want the weight for the down climb. Meanwhile. I looked down and saw Renita had returned with her hands full of obsidian, so I started down and for the first time understood the risk involved. It wasn't steep, or even terribly difficult, but the sharp glass edges were a reminder of the ever present danger. I had to use some for handholds, and they were solid, but still sharp. I stepped on one edge and it felt like I was standing on the edge of a razor but it didn't cut through my shoe. Safely reaching the bottom of the glass wall. Renita showed me her samples. We hiked along the base and she pointed out the beautiful flow lines of pumice and obsidian. Returning to the truck we loaded our samples,(more weight for the fifth wheel don't you know), and drove back home. What a crazy place! Clear skies.