OGOF AGEN ALLWEDD SOUTHERN STREAM PASSAGE
AN UNEXPECTED DISCOVERY by Jeff Morgan
Ogof Agen Alwedd, or to give it its common nickname ‘Aggie’ is situated in the centre of the vast amphitheatre of the Llangattock escarpment near Crickhowell in the Black mountains area of South Wales. It was first explored in 1946 by the South Wales Cave Club for a distance of approximately 1500 feet. In 1957 the Hereford Caving Club managed to pass the first boulder choke and break into the main chamber and eventually the main stream passage and beyond. The Hereford Caving Club and the Chelsea Pothole Club, though not necessarily together, then continued exploration of all major passages and this was more or less completed by around 1960.

At Easter 1962, Harold Lord was just finishing the first detailed and accurate survey. Myself, Ken Pearce and Bob Toogood were checking over to see if he had missed anything in the way of new passages. We entered the cave to have a look at Southern Stream Passage, which was at that time a low crawl of about a thousand feet long. It took us about an hour and a half to get to his last survey point, which was just where the stream disappeared into an uninviting low crawl about twelve inches high. We went down to have a look, and after about a hundred feet it sumped. However, on the left were a lot of loose boulders and shale, and as we had plenty of time, we decided to dig.
Three digs were started and after about ten minutes easy digging, Bob Toogood broke through into a small passage with lots of crystals over the floor. It was obvious no one had been in before. We went down the passage for about a hundred feet and came to another choke over the top of a large flat slab. This proved more difficult to dig than the previous one, but after taking turns at digging in a very awkward position for about an half an hour, I fell through into the stream below in a shower of rocks. The others followed and we pushed on downstream in high hopes.

The way on didn't vary much, it was either simple crawling occasionally over boulders, or low walking, and we didn't meet any obstacles until we came to a ten foot pitch. We knew we could get down quite well, but we weren't so sure about getting back up, so the next hour was spent carrying boulders up from the passage and throwing them down the ‘pitch’ so as to fill in a pool at the bottom, thus providing a ‘cone’ to climb back up. This done, we carried on down and into the stream passage again. Here the passage seemed to alter into a rift type of passage with various little waterfalls about two feet high. As we went further down, the rift began to get higher and the only thing that held us up were loose boulders which were removed if possible.

After continuing for about two hours the rift began to get choked with mud at stream level, and we had to start traversing along good ledges about twenty feet up. After three hundred feet, we emerged at a 'T' Junction - ‘The Master Cave.’ It was a wonderful sight, slow moving black water twenty feet wide, and at that time over five feet deep - we did not realise it was nearly two feet above normal. It was then decided to return at a later date with better equipment. The way back was very tiring and eventful only in that we came out with only one light still burning fourteen hours after leaving the entrance. Three weeks later Ken Pearce and Harold Lord returned with various other people to go as far as ‘T’ junction and survey out to the entrance. Ken did not have time to stay with them, and once they had started surveying he set off out on his own.

About three quarters of the way out his light failed and he had to wait about eight hours until the surveying party caught up with him. There must be a moral in that somewhere! They eventually got out after eighteen hours with nearly four thousand feet of passage surveyed.
A couple of weeks later we returned with a much larger team than before with the intention of exploring, photographing and surveying the Master Cave. I went upstream with Harold, and Ken and Bob went downstream. Upstream the cave got bigger and the water soon became only knee-deep running fairly fast, except in occasional deep pools. In some places the passage was a hundred feet high and the walls fifty feet apart. After walking up this passage for about half an hour, noticing many high inlets on the way, Ken Pearce and Bob Toogood caught us up. They told us that downstream only went for three or four hundred feet through deep water to a large sump.

Soon we come to a deep pool completely covering the floor, with the stream entering down a waterfall about six feet high at the other side. Various ways of getting round this were attempted but eventually the only way across was found to be by swimming, and climbing straight up the waterfall - quite interesting to say the least! Above the waterfall the passage developed into a large shattered chamber (now known as the fifth boulder choke) and after trying to dig through, we realised that it was the end. Slightly disappointed, we turned round and started to survey out. Before we had arrived back at the top of the waterfall though, Ken and Bob had managed to climb up to an inlet (now called BIZA passage) and shouted down to say that they were off to explore. Harold and I continued to survey back to ‘T’ junction, slow but fairly easy owing to the spaciousness of the passage.
Eventually we all met up again at ‘T’ junction, Les Salmon and his friends having turned up and surveyed the four hundred feet to the sump. Ken and Bob said that the inlet went for quite a way before ending up in two low crawls.

The trip out was again uneventful, we emerged in twos and threes over a period of about two hours. The total time underground this day was approximately twenty hours.
The survey was eventually plotted out and it was realised that the Master Cave was actually the main stream passage, and the fifth boulder choke is only a quarter of a mile, and in a direct line from the fourth boulder choke.
We then released the news of the discovery, and the Chelsea Pothole Club kindly surveyed ‘BIZA’ passage for us, contriving to find a passage of their own running off (Bat Passage) in the process. BIZA passage was plotted on the survey and was found to come within fifty feet of the fourth boulder choke. The total length of new passage explored was about two miles. Since then the sump has been dived by Steve Wynn-Roberts and Fred Davis of the Cave Diving Group. It went for a hundred and fifty feet to a submerged pothole in the floor, of unknown depth.
There has been a certain amount of digging at the end of BIZA passage, but so far without result. If it could be connected with the fourth boulder choke it would give one of the best 'round' trips in the British Isles.