The Mereless Gill

[Samouse1]

I haven't been down Meregill for years. Does this suggest that the mere water has another alternative route to God's Bridge other than the 'normal' way?

Yes, it definitely flows away down at the bottom there. Obviously there's some restriction that causes it to back up until it overflows into the "main cave"

 

[mikem]

Probably a series of restrictions, that mean it doesn't always perform as expected

 

[Lankyman]

Yes, it definitely flows away down at the bottom there. Obviously there's some restriction that causes it to back up until it overflows into the "main cave"

I wonder, has the flow been tested? Obviously, God's Bridge has to be the ultimate destination but does the water re-enter Meregill lower down or find a totally independent way through? It's very difficult solving this from my armchair!

 

[langcliffe]

I wonder, has the flow been tested? Obviously, God's Bridge has to be the ultimate destination but does the water re-enter Meregill lower down or find a totally independent way through? It's very difficult solving this from my armchair!

There are no obvious significant inlets (apart from Black Shiver) before the sump. Whether it joins between the downstream sump and Roaring Hole is another matter.

 

[Fulk]

Afternoon, Samouse, I took another look at our photos and I reckon that the points I've marked X–X on yours correspond roughly to those marked Y–Y on mine, and the new level of silt in your picture is rougly as shown by the green line on mine. This would imply that there is an extra 2 metres or so of what looks like rather unsavoury mud in your picture as compared with mine.
Here's yours:

 

[Fulk]

And here's mine:

 

[Fulk]

As you can see, the sediment in my shot is not at all shitty and horrible, as is evident in this next shot of our two intrepid explorers posing on their way down the slope:

 

[Samouse1]

I agree, the sediment has gotten higher! The bit at the bottom, where it is now higher, was actually the only horrible bit, very floppy and Welly trapping

 

[Samouse1]

After several trips, here are some observations on the height of the mere.

7/6- Mere full, overflowing into the cave
12/6- Mere ~5m below overflow
13/6- Mere ~6m below overflow, dropped another metre or so during 4 hour trip
19/6- Mere ~4m below overflow (rain since last trip)
23/6- Mere very nearly empty, ~23m below overflow

So it does drain away very quickly at the moment, 5 days at most to empty, presuming some rain fell on Ingleborough during that thunderstorm t'other night!

 

[mikem]

You can download local data from here and far gearstones (when latter corrects - not much yesterday):

Rainfall at Ingleton High Leys gauge - GOV.UK

Check the latest recorded rainfall at Ingleton High Leys gauge

check-for-flooding.service.gov.uk

Bull pot farm had a lot of rain over 5th to 9th, then no more until 14th & 17th, and another dump yesterday (has recently been very variable between quite closely positioned sites):

Speleodex - Rain at Bull Pot Farm

speleodex.co.uk

 

[mikem]

Anyway, it just means that the ground water levels haven't recharged yet

 

[Fulk]

After several trips, here are some observations on the height of the mere.

7/6- Mere full, overflowing into the cave
12/6- Mere ~5m below overflow
13/6- Mere ~6m below overflow, dropped another metre or so during 4 hour trip
19/6- Mere ~4m below overflow (rain since last trip)
23/6- Mere very nearly empty, ~23m below overflow

So it does drain away very quickly at the moment, 5 days at most to empty, presuming some rain fell on Ingleborough during that thunderstorm t'other night!

That's very interesting, Samouse, I'm sure that the Mere stayed up for much longer than that in the past.

 

[Badlad]

On 31st May it was overflowing into the cave. Very wet.

 

[mikem]

We have very similar with our dig on mendip, last winter was very wet so groundwater was full and the dig flooded for months, this spring it drained away much sooner and never got so high (the ongoing passage is very constricted with mud so takes some time, but drainage rates are very variable)