4 minute read
Caving Phil Hendy
Caving in winter
CHRISTMASand the New Year celebrations have been and gone, but there will still be a few months of winter weather, which will affect our caving activities. Most of our annual meetings and dinners were held before Christmas. It was good to be able to meet and talk with other cavers, many of whom had not been seen for more than two years.
It was also a time to remember “absent friends”, who either passed away during the epidemic, or through age or ill health decided not to risk joining a large gathering.
Winter weather inevitably brings increased rainfall, as well as the possibility of ice and snow. High rainfall can cause certain caves to flood, as happened in October when five cavers became trapped by rising water in Eastwater Cavern at Priddy.
The fire brigade were tasked with pumping the stream to divert it from the entrance and allow a party of cavers from Mendip Cave Rescue to enter and bring the trapped individuals to safety. While not particularly flood prone, it would have been advisable for the group to have sought local knowledge before entering the cave. There are plenty of caves on Mendip which do not flood.
Accounts by early cavers often recall “epic” trips where high water or flash floods made progress difficult or even impossible. It was 11 years after Swildon’s Hole was first entered before water levels were low enough to allow a party to descend and explore beyond the Forty Foot Pot, and a further ten before Sump One was reached.
There were, of course, other factors than the weather which slowed exploration, but in recent years caves have flooded much less frequently.
One advantage to winter caving is that generally carbon dioxide levels in caves tend to be much lower. The presence of this gas at higher than normal levels was known for a long time in some caves, but the phenomenon seems to have become more widespread. Either that, or we are more aware of it.
The source is a mystery; at one time it was thought to be caused by decaying vegetation, but farming practices on Mendip have not changed sufficiently to have made a difference. Of course, the action of slightly acidic water on limestone releases the gas, which is usually encountered in the deeper parts of the cave where there is less air movement.
Levels tend to be higher in the summer months and some believe that changes in atmospheric pressure (and increased water flow) will flush the gas from the cave. Carbon dioxide causes fatigue, breathlessness and headaches (and in high doses can lead to death). It is possible that in the past, these symptoms were assumed to be due to lack of fitness or over-exertion.
Dry caves generally have a stable temperature, but winter streams can reduce this substantially and in the past several rescues were necessitated by poorly-clad cavers getting wet and developing hypothermia. Long queues waiting to ascend the Forty Foot Pot in Swildon’s Hole and having to stand in the spray and draught, were particularly vulnerable.
After the floods of 1968, an alternative route to the Forty opened up, and better, specialist clothing, has made hypothermia extremely rare. The biggest danger now appears to be the long walk back across the fields from
With PHILIP HENDY
some of our more remote caves, while wearing wet gear in frosty or windy conditions. Many of us have had to stand in front of a fire, or be assisted in undressing, when our clothing has frozen on to us.
This is where the caving huts come into their own, as nothing speeds the retreat from a cave in winter than the prospect of a hot shower, warm dry clothes, and the likelihood of a fellow caver providing a pot of tea and maybe a homemade cake.
As well as sport caving, digging still continues, though most of us choose to put our efforts into some underground excavation rather than having to put up with the elements on the surface. Changing into digging kit usually takes place close to the site, which involves undressing in the open. We refer to this as “character-building”.
Some digs have site huts for this purpose, while a kind farmer may offer the use of a barn. Afterwards, there is always the chance of a brew at the hut, or more likely, a pint and debrief at the local. Caving and digging takes place whatever the weather, although consideration has to be made regarding the risk of flooding.
Some cavers prefer to go underground in winter, when higher water levels make for a more sporting trip. It is as well that the Mendip caves have enough variety to suit every caver, whatever their interest or ability.
