Cambridge Underground 1980 pp 8,11


From being a place rarely visited by the club, this pot has rapidly become a very popular (?) trip with certain aficionados in the club. Initially interest was stirred by the number of sumps in the place. The fact that all the more promising sites were at the opposite end of the cave from the entrance did little to abate enthusiasm.

Kamikaze Sump

In June 1978 the first attempt was made on Kamikaze sump. This trip ended about 50 feet from the sump when the members of the party decided unanimously (2-0) that they were bored with the cave, and the diving gear was carted out again. The next attempt was in March 1979, and this time a diver was deposited in the sump complete with diving gear. After 20 feet a low slope down to the left descended to a depth of ten feet. A hamster sized bedding plane led off, so the sump was left for the next generation of tyros, who will undoubtedly have a bucket and spade as an integral part of their diving gear.

Earthworm Passage

A very brief period of sanity intervened, but the head banging started again about a month later. The target this time was the sump under Earthworm Passage. This is at the same level as Kamikaze sump but is active. A five foot descent in a narrow rift dropped into a low bedding. After 30 feet this broke into a large cross-joint with a small airbell at one end. Flailing around in his wellies the diver suddenly wished he had brought some proper diving gear with him. This was supplied the following day with the aid of a number of 'heavies'. From the crossjoint a tunnel led on downwards for about 30 feet to a choke. Through a squeeze to the left a heavily silted bedding plane could be seen continuing on down - another job for the bucket and spade brigade!

On the way out, a number of the 'heavies' large of girth and lacking in fitness found that carrying both themselves and gear out of the cave was too onerous. The latter was abandoned to be retrieved by those with larger muscles but smaller brains, while the former almost became part of the underground scenery.

Chert Crawl

Then it was autumn and the sump under Chert Crawl. This was at least considerate enough to 'go' before closing down. 20 feet of sump led to ten feet of passage and an impassable sump: 3-0!. There is another sump close to this one on the Earthworm Passage side, but it wasn't tried as it looked the least promising; it is in a very narrow rift. Sod's law dictates it will go!

Antler Pot Inlet

So much for the sumps at the bottom; what about the Antler Pot inlet sump? Acting on the erroneous belief that not all sumps can't just not go some of the top theorists in the club descended Magnetometer once more. The approach to the sump is, in the modern parlance, restricted. The sump is even more restricted. Moling his way past a silt bank the diver soon found the sump became distinctly welly sized; he backed out in 'poor' visibility. The sump can't be very long but it is very small. In theory it should go.

Cow Close Passage

And so off to the Cow Close Passage sump - the club's thinkers are not easily deterred by minor set-backs. In the event, this sump proved to be the complete vindication of all their theories. The other sumps being merely the exceptions that proved the rule. The sump is at the end of what Northern Caves describes as an 'old inlet passage at Holes Junction'. The description is probably wrong.

At Holes Junction, the water from that inlet and others drops down a series of small vadose rifts to two sumps which have been dye-tested to Pendulum Passage below Caton Hall. On the other side of the Junction, the Cross System passages have considerable vadose modification and are small, at least until the line of the Caton Hall - Milestone Chamber fault is encountered. Neither can provide the continuation for the large phreatic drain of Styx Passage and Easy Street, generally 120 square feet in cross section and the most notable feature of Magnetometer.

'The inlet passage' is of that size initially, washed out by the pirate stream which enters from the roof halfway along, after which the banks of fill reduce it to hands-and-knees height or less, before terminating in the canal and sump fed by another smaller inlet.

The sump proved to be an easy five foot free-dive to 30 feet of muddy rift rising to a complete stal and boulder blockage. With the view that the passage might be the continuation of the major phreatic drainage, Rob Shackleton, Julian Griffiths and Andrew Nichols began digging at the blockage the following weekend. Eight very sordid trips followed, manufacturing a fifteen foot tunnel to break through on 27th January 1980.

The final body sized section dropped the trio into the continuation of the rift, which substantiated their earlier view by being several feet lower than the floor of the canal. A climb up into a muddy roof crawl and a further descent past a fine flowstone cascade brought them to more crawling and a squeeze which Julian alone was able to pass. He made further progress, mainly roomy hands-and-knees, to a partial stal blockage. As both this and the previous squeeze needed modifying, and Rob and Andy were suffering from 'flu, it was decided to postpone further work. Some 200 feet of new passage were entered on this trip.

Returning a couple of weeks later the stal blockage was bypassed by a short dig to one side and a further 250 feet of crawling passage was explored to a nasty duck. Past this, 50 feet of passage led to a tight bend which would need some modification to get round. A number of side passages were also explored.

It would seem that this passage does represent the earliest drainage route in Magnetometer, emerging at a resurgence long since destroyed by the glaciers. Certainly it would not have borne any relationship to the present Brants Gill drainage system. As befits a passage of this age it is crammed full of glacial fill and does not provide very appealing caving.

Julian Griffiths
Andrew Nichols

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