The Old Ruminator
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Today.
Return To Quarter Way Up Hole
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The Old Ruminator
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We still have a cold outward draught. My theory of a missing %50 of the St Dunstans Well catchment would indicate more relict inlets from the west. Shatter and Withyhill are around 167m OD and the QWUH Pit is still well above that level. So for the moment its all about going on down with the fault wall. Nearly all FCQ caves are formed along strike or the N-S fault pattern. There are three prominent faults in the QWUH area.
The Missing Catchment Theory.
Yes its just that. A theory. It does place QWUH at the centre rather than at the margin of the catchment where it is today. The missing part has been captured by the downcutting of the Askwick Grove valley and the erosion of the quartzitic strata forming the dam for the catchment. That breached by the slip strike Withybrook Fault. Although having the steepest strata and the longest pericline on Mendip Beacon Hill has been much reduced by surface erosion probably truncating any part of Shatter Cave formerly existing in the Black Rock Limestone. Same can be said for QWUH and the ingress of Robert some 45,000 years ago. Much of the BRL has been covered by Head a solufluction deposit . This today has meant that all modern streams and sinks no longer sink in the BRL. They are contained on the surface to sink in modern swallets like Midway and Blakes Farm. Midway has cut its own stream channel in the Head. The unknown factor is what part Fairy Cave played. Clearly its a higher inlet from the west formerly draining part of the lost western part of the catchment. It has a comparison with the lower Stoke Lane streamway beyond Sump Two with its now mis fit stream running along strike and contained by the quartzitic strata until the resurgence is met.
Fault and Strike Cave Development South Side of FCQ
QWUH is no 24 and X is approx. where The Pit dig is. The remaining fault structure , apart from the Withybrook Fault, is best seen at the entrance to Hillwithy Cave.
I shall post this and may continue.
The Old Ruminator
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Withyhill exposed 1972. Note the strata blast pattern up to the fault where the white dots are. The same fault probably forms Broken Curtain Chamber.
The Old Ruminator
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Steep strata and the Withybrook slip strike fault plane near Shatter Cave c 1970.
The Old Ruminator
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Quarry floor c 167m OD. Surface 200m OD . South Face c 1970 - 72
The Old Ruminator
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St Dunstan's Catchment and Ashwick Grove etc from the air.
The Old Ruminator
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FCQ 1970's.
Walking back from Shatter Cave.
Walking back from Shatter Cave.
The Old Ruminator
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Withyhill 1972 showing blast pattern and guiding fault now mostly obscured by undergrowth.
The Old Ruminator
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So to sum up in theory with no dateline.
The slip strike Withyhill Fault displaces the bedding by at least 50m dislocating the quartzitic strata to provide an exit for the proto catchment.
Phreatic drainage probably originating at the Black Rock Rock Limestone and Lower Limestone Shales boundary.
Shatter develops as the primary drain but at some point gets captured by Withyhill. Both have classic phreatic / vadose transition with the Withyhill relict conduit only enlarging beyond Pearl Chamber the point where you actually enter Shatter Cave. Both caves end very close to the surface where a dry shallow valley runs.
The Mells valley gets cut down as does Ashwick Grove. The plateau above the caves also gets much reduced. The water table in the catchment drops . The phreatic levels are abandoned into the transitional vadose phase. That process continues. The active streams are now below quarry floor level. Withyhill has a mis fit flood stream probably due to sink clearance at Withybrook Slocker. Flood pulses have muddied the lower cave and undermined sediment banks though this is all post 1972. A shame that an overspill gulley was not cleared from Withyhill to Hillwithy in the 1970's. A later erosion gulley can be seen between the two caves.
Sequential periglacial ice eras play a part. Head gets deposited on the BRL obscuring any possible ancient sinks. Surface streams are now trapped by those deposits. All sinks are now modern or like Stoke Lane Slocker mis fit.
Blue Ice fractures and shears stal deposits in the Shatter/WL relict conduit. You dont see any as far as I know in Withyhill until you enter the capture branch to Shatter Cave. QWUH gets exposed.
Fairy Cave gets detached from its origins by the down cutting of the valley probably during periglacial conditions. It joins with the Hilliers system to resurge at a higher level beyond Red Room. We made a sound contact by driving a post in on the surface during radio location here years ago.
The western section of the catchment is lost to later risings in Ashwick Grove.
The slip strike Withyhill Fault displaces the bedding by at least 50m dislocating the quartzitic strata to provide an exit for the proto catchment.
Phreatic drainage probably originating at the Black Rock Rock Limestone and Lower Limestone Shales boundary.
Shatter develops as the primary drain but at some point gets captured by Withyhill. Both have classic phreatic / vadose transition with the Withyhill relict conduit only enlarging beyond Pearl Chamber the point where you actually enter Shatter Cave. Both caves end very close to the surface where a dry shallow valley runs.
The Mells valley gets cut down as does Ashwick Grove. The plateau above the caves also gets much reduced. The water table in the catchment drops . The phreatic levels are abandoned into the transitional vadose phase. That process continues. The active streams are now below quarry floor level. Withyhill has a mis fit flood stream probably due to sink clearance at Withybrook Slocker. Flood pulses have muddied the lower cave and undermined sediment banks though this is all post 1972. A shame that an overspill gulley was not cleared from Withyhill to Hillwithy in the 1970's. A later erosion gulley can be seen between the two caves.
Sequential periglacial ice eras play a part. Head gets deposited on the BRL obscuring any possible ancient sinks. Surface streams are now trapped by those deposits. All sinks are now modern or like Stoke Lane Slocker mis fit.
Blue Ice fractures and shears stal deposits in the Shatter/WL relict conduit. You dont see any as far as I know in Withyhill until you enter the capture branch to Shatter Cave. QWUH gets exposed.
Fairy Cave gets detached from its origins by the down cutting of the valley probably during periglacial conditions. It joins with the Hilliers system to resurge at a higher level beyond Red Room. We made a sound contact by driving a post in on the surface during radio location here years ago.
The western section of the catchment is lost to later risings in Ashwick Grove.
The Old Ruminator
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Post 1972 mis fit stream erosion channel from Withyhill.
The Old Ruminator
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The Withyhill - Shatter capture link showing bed displacement and theoretical line of the Withybrook Fault.
The Old Ruminator
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I just realised this is Withyhill before clearance. See the blast pattern behind the two cavers. Date then c 1972 / 73. QWUH/HWUH behind the boulders to the right.
The Old Ruminator
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Another session yesterday.
The Old Ruminator
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Looking again I think that HWUH and QWUH are at Y. Also clearer the fault I have marked as a line. Withyhill is X.
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