Saturday, July 12, 2008

[trip] Return to SEC's Rushin' Rift

This GVKS weekend (2008-07-12), Nikki Green and I did a two-person "squeezefreak" trip to survey the upper passage at the top of the Rushin' Rift in Shovel Eater Cave. We were one of the last teams in cave, at around 10AM, and hit the tail-end of rope traffic in the entrance series of the cave. At HHA15 we picked up a 9mm rope, left a note for Mark Minton and Yvonne Droms (as a safety precaution for our two-person survey), and headed for the nearby Rushin' Rift. We found Bob Zimmerman's team before we found the Rift, and they stuck Nikki down two tiny leads which didn't go. They claimed to have checked out the Rift on the way in, and found it to be silent; we confirmed this ourselves, no sign at all of "The Devil's machinery", so apparently the water within this chasm is intermittent.

I rigged the 50 foot drop, though we did not rappel into it - rather we used the Y-hang as aid to go straight back into the upper rift passage. We shuffled back to the unlabeled calcite chunk cairn (CN1) which marked the end of the previous survey, located just before this passage goes from "small" to "tiny". Before we could mark our first station, the hungry rift ate our only roll of flagging tape; thus, all stations on this survey are marked with blue sharpie on rock.

This upper rift passage is capped by a fault plane, dipping about 20 degrees in a generally East direction, which frequently appears as a smoothly-sculpted calcite vein in the ceiling, and sometimes as oddly-shaped phreatic proto-passage formed within once-fractured rock. Freshly-broken crystal gives off a sulfur smell. An extremely narrow canyon is incised into the floor, usually too narrow to eat a body, but almost always the perfect size to eat the conveniently-placed foot or survey tape. At several places - notably near our first station and past our last station - rocks dropped down this canyon can be heard to tumble down quite an impressive distance, what I would estimate to be at or beyond 50 feet, though "tumbling rock" can be deceiving. At one point, we clearly heard hammering, which we later discovered to be the work of Bob Z's team. Airflow was never more than "slight", if that. Paleoflow direction is likely in the direction of our survey - away from the cave's main passage, and generally Northeast - at least in the upper rift.

Representative sketch of the upper Rushin' Rift - tiny passage with a nasty canyon incised into the floor.

We surveyed the entirety of what I "scooped" on the previous trip. I had estimated this to be on the order of 200 feet, but the miserable nature of the passage caused me to overestimate by 2X. At the end, the passage turns down the dip of the fault plane, losing around 15 feet of elevation, where the still-hungry rift devoured Nikki's digital camera (sorry, Nikki!). Finally a "room" is reached, which is comfortable enough for two people to stand and eat lunch; rocks dropped down here tumble down what sounds like a terrifyingly-deep chasm, an experiment that I repeated many times in the name of science. Beyond, the passage becomes too tight to follow, but the deep canyon may be accessible just beyond our last station, as the canyon widens in a sharp meander. Upon finishing, we de-rigged the unused rope and returned it to HHA15.

We surveyed 115 feet in a painful 10 shots. I do not consider the upper Rift lead to be killed yet. Rather, I believe that the only way to further explore the Rushin' Rift is to ignore the too-too-tight lower rift passage, and to rig rope from the top passage and enter the rift from one of these upper access points.

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