Caves in relation to stratigraphic member

[TheBitterEnd]

Just wondering if anyone has ever looked at where cave passages occur with respect to stratigraphic member - e.g. Cove, Gordale etc.? Obviously there are several dimensions that could be measured, volume, length, position vertically within the bed, etc.

The new Cave and Karst of the Yorkshire Dales book has things like some caves in relation to shale beds but as far as I can see not where they are in the stratigraphy...

 

[Pitlamp]

Will send a p.m.

 

[TheBitterEnd]

I was there, hence the question    whilst stratigraphy was mentioned a lot, cave passage in relation to the beds did not seem to be quantified. Thanks for the quick response though.

 

[Pitlamp]

Send me a P.M. if you think I can help - but I'm far from expert I'm afraid.

 

[gus horsley]

There are clearly correlations between stratigraphy and passage development.  Apart from the obvious impermeable beds such as shales which impede the downward flow of water in horizontal strata, variations in the lithography of the various beds that make up the main limestone members will influence cave development, probably the best known being the Porcellaneous Band.  Some individual beds are extremely compact (such as PB) where others may display variations in porosity (limestone actually is classed as a non-porous rock, as opposed to chalk which is porous) and this would possibly not only infleunce passage size and cross-section but also the amount of phreatic tube development.

I haven't done any work on limestones but I've studied some of the effects of hydrothermal systems on rock types and they behave in a remarkably similar way, albeit the opposite way round (descending karst waters versus ascending hydrothermal solutions).

Plenty of scope for research I think.

 

[grahams]

There are clearly correlations between stratigraphy and passage development.  Apart from the obvious impermeable beds such as shales which impede the downward flow of water in horizontal strata, variations in the lithography of the various beds that make up the main limestone members will influence cave development, probably the best known being the Porcellaneous Band. 

Littondale's Bown Scar Cave, Scosca Cave, Litton Fosse and Waterfall Cave (in Penyghent Gill and possibly associated with Litton Fosse) are good examples.

 

[sluka]

Carstification in ANY case follow the weakest directions in a bedrock. It is combination of chemical composition (stratigraphy), planes, faults and microfaults, gravity, etc. The computer modelling of profiles made by such general karstification made Jakopin and Sustersic from Ljubljana, Slovenia somewhere in middle of 80th.

 

[TheBitterEnd]

I agree with all the foregoing. My question was really about has anyone quantified it? As mentioned above and is fairly obvious on the ground, much cave development is controlled by faults/joints and to a lesser or greater extent disregards bedding. It also seems fairly obvious that topography is a major influence.

But I just got to just wondering if anyone has any data on length/volume of cave in particular beds ? esp. in the Great Scar Group?

 

[bograt]

The Peak Cavern Survex illustrates examples of this rather well.

 

[graham]

In Co. Clare, where the geology is fairly simple, it can clearly be seen that the majority of known cave passage is found preferentially in only some beds.

See the introductory chapters by Mike Simms in The Caves of County Clare and South Galway.

 

[NigelG]

Re Gus Horsely's statement of the effect of an impermeable formation (an aquiclude).

In some situations it can also confine water below it.

The eample I know particularly but I am sure is not unique, is that of the phreatic phase of the long-fossil Blacknor Hole, on Portland. There,  a chert seam about 100mm thick within the limestone trapped what seems to have been two concurrent, roughly parallel, inlet streams below it, creating extensive anastomoses between them in the area approaching their meeting-point - named literally 'The Confluence'. Eventually vadose down-cutting, probably from base-level fall, left the chert roof high and dry.

The rock is the Late Jurassic's Portland Formation; the detail bed being the Cherty Series (modern texts seem to ignore such internal variations even where plainly significant, on Portland commercially as well as scientifically). The structure is the gently-dipping Southern limb of the Weymouth Anticline, of Tertiary age; the folding created a strong rhomboidal joint pattern. 

Elsewhere in the area, we see passage morphology apparently affected by the limestone, but the caves lost their catchment area and many passages to coastal retreat, and are now highly fragmented by quarries, so trying to deduce what went where and how is almost impossible.