01-05-2007

01-05-2007

Big news! This taken from Descent magazine:

George’s Choke Yields to Saintly Power

by Stephen Macnamara

Photos:
George’s Choke, photographer Chris Jewell, subject Stephen Macnamara
Canyon passage in the Mayfly Extension, photographer Chris Jewell, subject Stephen McCullagh
The downstream terminal sump, photographer Chris Jewell, subject Stephen McCullagh
New digsite at terminal sump, photographer Chris Jewell, subjects Stephen McCullagh (L) and Stephen Macnamara (R)

The Shannon Group has been busy over the past couple of months, and the hours of toil have paid off. On Saint Patrick’s Day (17th of March for the heathens among you), George’s Choke finally relented, to admit a group of three cavers into the downstream Mayfly Extension. The extension, named by the first explorers in the eighties, became inaccessible after the repeated collapses of George’s Choke. The nails were put in the coffin when the original cave entrance series collapsed about fifteen years ago.

The 2005 breakthrough from Polltullyard into Shannon allowed a new assault on George’s Choke to begin in earnest at the start of 2006. Some fifteen trips of gear transporting, digging, scaffolding, cementing, photography, surveying and lead pushing have been made, the average trip length being nine hours.

In September 2006, the group made a significant push through the worst of the choke into apparently stable, large boulders beyond. This trip was curtailed by light failure. Undeterred, we returned in the next month. Unfortunately, the choke now decided to reassert itself, almost incarcerating one of our key members … and another retreat was necessary. The subsequent trips were spent redoubling the scaffolding effort and applying lashings of quick-setting cement (mixed in a few saucepans which were retired from culinary duties for the purpose).

Saint Patrick’s Day was bound to be a lucky one, and we decided to retry the push. Back in the large stable boulders, an interesting right angle squeeze at floor level was immediately followed by a tight slot under a boulder into water. One further squeeze up through boulders found us looking into a sizeable chamber with the stream emerging in front of us. A short stroll led us out of the boulder choke and into the clean-washed streamway of the Mayfly Extension!

In comparison to the boulder-strewn passage upstream of George’s, the downstream extension is a luxury. Three hundred metres of stomping passage is only interrupted once by a minor choke. Much of this length is beautiful canyon streamway.

We quickly reached the downstream terminal sump, where the water disappears to resurface three kilometres later at Shannon Pot, the source of the Shannon River. An old dive weight was still lying on the ledge beside the sump. We did not spend too long here because the water level had risen by half a foot. The squeezes in George’s Choke were decidedly wetter on our return, and somewhat alarmingly, the normal crawl out of the choke had sumped off! Fortunately, we found a high level route before making a sprint for the surface.

On the latest trip, we checked the terminal sump for diving possibilities with the help of Chris Jewell and his diving mask, and concluded that there was indeed potential. A climb up into the boulder choke above the sump leads about ten metres further downstream, and then drops back to stream level, with a voice connection back to the sump chamber.

However, non-divers need not despair yet. About fifteen metres back from the sump chamber, before the boulder choke starts, Steve McCullagh spotted a sculpted ledge running along the left wall just below ceiling level. With a boost from Steve, I climbed up and crawled twelve metres into this sheltered tube, which seems to skirt around the edge of the passage and hence bypass much of the boulder choke. I rigged a handline and we soon made five metres’ progress through easily removed rocks. This is the most pleasant digsite we have encountered in Shannon yet, with a solid floor, wall and ceiling. Some minor shoring will be necessary, but the site seems very promising.

Work on the survey is continuing in parallel with digging. In addition, George’s Choke needs a bit more shoring work to make it safe for the level of traffic we expect over the coming months. We need more members please!

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