June 7, 2003 - Lehman Cave, Nevada
I left Las Vegas at 10:00am to start the horizontal control network for the Lehman Cave mapping project. I arrived at Great Basin National Park at 3:00pm and meet my contact at 4:00pm. The survey was started at 4:30pm at the entrance to the cave to bring in the basis of bearing for our map. After the second traverse station was turned through the first problem arose with the survey process. We are using a Sokkia Set 3 Total Station and the optics is not capable of gather light as well as some of the newer stations on the market. When sighting on the prism at distances over 50 feet, the cross hairs where not visible with the light source that was being used. The standard caving head lamp was not working well and another type of light source will have to be used. Condensation was another problem. Condensation would form on the optics from my breath and fog up the lenses making it impossible to sight on the targets. One option to fix this problem is to get a heating plate to put in between the gun and the tripod, the other is to hold your breath while you turn the angles. How long can you hold your breath? I guess I will find out. The slow survey process of turning eight angles and shooting four distances per station continued on into the night. By 11:00pm I was getting tired and started to slow way down because of fatigue. In order to avoid making any major mistakes in the control survey I ended work at 11:30pm. Unfortunately because of the problems that were encountered only five stations were traversed through on this trip. After packing all the survey equipment out of the cave and driving to the campground it was about 1:30am on Sunday before I got to sleep. I woke up at 9:00am and headed back to Las Vegas. As a Grotto we chocked up this trip as a shake down for our survey methods and we hope to have ironed out most of the problems. Only time will tell. Our next trip to Lehman cave is scheduled for the weekend of June 14th.
Trip reporter: Steve L. Deveny
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