Pitlamp
Well-known member
Sleets Gill is one of a series of caves around the Dales which share similar characteristics:
* Fed mainly by percolation flow (autogenic).
* Act as a flood rising only.
* Normally drain to a resurgence lower than the cave entrance via immature underflow passage.
* Flood response highly unpredictable; may or may not be delayed (depending on various factors).
Some examples are:
Sleets Gill Cave
Hemplands Rising
Mammary Pot
Pool Bank Cave
Preacher's Cave
I've been associated with all of these over the years to a greater or lesser degree and have seen some alarming things. For example, when a bunch of us reopened Mammary Pot a few years ago we were chased out of what was then a dig by water rising from below during a heavy rain event. The depression in which this cave lies then became a resurgence about 15 minutes later. Normal water level is 8 m below this point. Assuming the water had been rising at a constant rate, it'd probably taken less than 60 minutes to rise by 8 m.
Another example was at Preacher's Cave. This starts as a 4.5 m shaft leading to a further descent of maybe 2.5 m to reach the main sump pool which is normally static. I kitted up at this point before heading in for a working dive at the (then) end of the sump. When I returned to dive base all my tacklebags were submerged so I scooped them up, swam up the slope and surfaced at the base of the entrance shaft. The water was rising noticeably so I decided not to dekit as normal and simply let the rising water lift me up the shaft to the surface. 5 minutes later the shaft was brim full and starting to resurge; it had been like riding up on a gentle elevator and (for once) I had no tank hauling to do.
On both these ocasions it was that day's rain after a long wet period (like now) which caused such fast water level rises. Sleets Gill Cave is analagous to these two sites - but much longer; this is why I wouldn't dream of going in there at the moment and why I think Langcliffe's 2 dry weeks rule of thumb is excellent advice.
* Fed mainly by percolation flow (autogenic).
* Act as a flood rising only.
* Normally drain to a resurgence lower than the cave entrance via immature underflow passage.
* Flood response highly unpredictable; may or may not be delayed (depending on various factors).
Some examples are:
Sleets Gill Cave
Hemplands Rising
Mammary Pot
Pool Bank Cave
Preacher's Cave
I've been associated with all of these over the years to a greater or lesser degree and have seen some alarming things. For example, when a bunch of us reopened Mammary Pot a few years ago we were chased out of what was then a dig by water rising from below during a heavy rain event. The depression in which this cave lies then became a resurgence about 15 minutes later. Normal water level is 8 m below this point. Assuming the water had been rising at a constant rate, it'd probably taken less than 60 minutes to rise by 8 m.
Another example was at Preacher's Cave. This starts as a 4.5 m shaft leading to a further descent of maybe 2.5 m to reach the main sump pool which is normally static. I kitted up at this point before heading in for a working dive at the (then) end of the sump. When I returned to dive base all my tacklebags were submerged so I scooped them up, swam up the slope and surfaced at the base of the entrance shaft. The water was rising noticeably so I decided not to dekit as normal and simply let the rising water lift me up the shaft to the surface. 5 minutes later the shaft was brim full and starting to resurge; it had been like riding up on a gentle elevator and (for once) I had no tank hauling to do.
On both these ocasions it was that day's rain after a long wet period (like now) which caused such fast water level rises. Sleets Gill Cave is analagous to these two sites - but much longer; this is why I wouldn't dream of going in there at the moment and why I think Langcliffe's 2 dry weeks rule of thumb is excellent advice.