12MB PDF - Association for Mexican Cave Studies

so Paul and I started digging at thecobble floor, releasing vast cloudsof silt in the process. After severalminutes of this we seemed to bemaking little progress, so I grabbedthe spool and tried over nearthe left wall, which seemed to be alittle higher. Sure enough, I managedto plow on through and the fiveof us swam on into a sloping passage10 meters wide by 4 meters high, tyingoff on the floor at a depth of85 meters.As soon as I finished the knotsat 85 meters there was a loud blastaccompanied by a sharp concussion asone of my two sealed beam primarylights imploded. This is a fairlycommon occurrence, as the slightestscratch or imperfection will generall:cause a sealed beam bulb to implodebelow a depth of about 60 meters,but was nonetheless distressing sinceit thoroughly trashed the light andI had to spend a couple of extra minutesgathering up the pieces (wedon't like trashing up underwatercaves any more than we do air-filledones).Our exit was marred by a bottleneckof divers at the 55 meter constriction,where zero visibility (asopposed to the 15 meter visibility wehad enjoyed coming in) made findingthe best route out difficult, evenwith the aid of the well-belayedguideline. Since the water was warmerthan we had anticipated (about19°C) and I was trying out my newdry suit, the two hours of decompressionstops we required before surfacingweren't t.oo bad.On our third dive Dale, Steveand Ken extended the line another 18meters to a depth of 95 meters (atotal penetration of 175 meters)reporting another low area just a­head, beyond which the slope appearedto steepen again. We named theimpressive area before the 55 meterconstriction Sala de Piedra , andthe large area beyond it the Pacesetter'sPassage in honor of thetwo original explorers of the cave.Nacimiento del Rio ManteSince there is some above-watercave at the entrance and plenty ofmountain behind it, we were hopefulof finding some big streamway pasta short, shallow dive at the RioMante. However, on dive number 4(the first dive at Mante), Frankand Terry pulled their way along a5-8 meter wide by 5 meter high conduit60 meters to a depth of 13 meters,at which point the bottom droppedout! The only route continueddown a long, narrow pit 30-50 metersby 2-4 meters, from which all ofthe considerable water flow was gushingat a rapid rate. They haltedtheir vertical descent down the pitat a depth of 85 meters. Decompressionin the warm (27°C) water was24made interesting by the calcite crystalwalls and a small troglobiticisopod, which was sighted near theentrance at a depth of 6 meters.On dive #6, Paul and I ran abranch line horizontally at a depthof 55 meters, then descended diagonallyto a depth of 85 meters. Ondive #8, Frank and Terry descendedto the same point, where they sightedseveral more of the isopods (preparingto dine on our line?).On dive #9, Paul and I extendedour branch line 18 meters to a depthof 101 meters, at which point (168meters penetration) we could see thenear-vertical pit continuing to