17MB PDF - Association for Mexican Cave Studies

155NOTES ON THE EXPLORATION OF SOTANO DE LAby Richard SchreiberSILLETAThe entrance to S6tano de la Silleta was located on 22 Decemberby a reconnaissance party consisting of Dan Evans, TonyThompson, Kirk Holland, Ken Krans, Richard Schreiber, and a Mexicanguide.On Sunday morning, 25 December 1966, after spending Saturdaynight camped in Gruta de Navidad, an initial exploratory team,consisting of Kirk Holland, Dave Nelson, Tony Thompson, and RichardSchreiber, began the 800 to 900 foot vertical climb from Grutade Navidad up to the entrance of S6tano de La Silleta. The partycarried a 600 foot, 270 foot, and two 150 foot lengths of nylonrope plus the normal complement of vertical gear, food, and cameraequipment. The hike took a great deal of time and energy as thetrail was extremely steep and did not extend to the entrance. Itwas necessary to make our own trail for roughly 800 feet throughthe thick growth at the crest of the mountain ridge at the base ofLa Silleta. This unusual limestone pinnacle rises 400 feet higher.The elevation of the entrance to S6tano de La Si1leta is around6500 feet and pine trees are present, though not in abundance.When we reached the entrance we discovered that Kirk had lost hiscarbide lamp.One end of the 600 foot rope was lowered into the S6tano andthen tied off at about 350 feet. Richard rappelled down to findthat the drop was only 155 feet but that the pit continued downwardin a broad, partial spiral at an angle of 45 to 55 degrees.Because of the nature of the slope, it was decided to use the fUll600 foot length for the drop and the rest as a handline down thewet, slick slope. Dave, Tony, and Kirk rappe11ed into the pit.Kirk without his light looked around near the base of the dropthen returned to the surface to search for the lamp.Richard, Tony, and Dave worked their way down the wet flowstoneslope descending for about 250 feet, vertically, until thepit appeared to pinch out and end. Close observation produced twosmall openings which were actually one diVided into two by flowstone,making both openings about 2 by 2.5 feet. Through theseopenings a strong air movement was noted and a small trickle ofwater flowed. Here a 150 foot length was rigged because immediatelyon the opposite side a short drop was discovered. Richard,followed by Tony and Dave, made this drop of 30 feet. From herethe passage continued downward for roughly 120 feet, vertically,varying in width from 15 feet to 40 feet with ceiling heights ofup to 100 feet. The floor of the passage was wet flowstone. Massiveflowstone and other speleothems were found along the passage.After following this passage downward we found that it intersecteda horizontally-developed cave.At this point we split into two units: Tony and Dave wouldgo to the left and Richard would go to the right. The passage tothe left extended for about 400 feet and terminated in a dome. Itvaried in width from 15 feet to 40 feet with ceiling heights from6 to 70 feet or more. Many speleothems of all varieties werenoted. The passage to the right consisted of a low, wide streamcrawl for roughly 150 feet, then the ceiling increased up to about