map of the geological and topographical features of the ingleborough district
- Thread starter alastairgott
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I believe Hammy is correct, there may be other reasons but mainly its the joints and bedding planes which the water follows. Water gets into these and makes them bigger. If you think about water in a crack it is essentially in contact with two surfaces (either side of the crack) and so can dissolve twice as much rock as water just sitting on the surface of the limestone (which is only in contact with one surface, runs-off, evaporates, etc).
Joints are caused by techtonic forces (movement of the earths crust) which also cause faults. The difference is that a joint is just a crack, whereas a fault has some movement (horizontal, vertical or both). Your assumption that the water would make it to the sea underground is may not be correct because faults cause changes of rock type at a given elevation. A good example of this is in Barbondale where the Dent fault runs up the valley. The rocks on the Howgills side (north) are sandstone and the rocks on the Casterton side are limestone. Any water sinking in the limestone (if the valley was not there) would hit the sandstone and dissolve the limestone along the fault, so it's direction would be controlled by the fault.
The up shot is that there is no "formula" for where a cave happens to be, it is a complex, chaotic process and they are where they are
Joints are caused by techtonic forces (movement of the earths crust) which also cause faults. The difference is that a joint is just a crack, whereas a fault has some movement (horizontal, vertical or both). Your assumption that the water would make it to the sea underground is may not be correct because faults cause changes of rock type at a given elevation. A good example of this is in Barbondale where the Dent fault runs up the valley. The rocks on the Howgills side (north) are sandstone and the rocks on the Casterton side are limestone. Any water sinking in the limestone (if the valley was not there) would hit the sandstone and dissolve the limestone along the fault, so it's direction would be controlled by the fault.
The up shot is that there is no "formula" for where a cave happens to be, it is a complex, chaotic process and they are where they are
graham
New member
khakipuce said:The up shot is that there is no "formula" for where a cave happens to be, it is a complex, chaotic process and they are where they are
It is by no means wholly chaotic, as it can be seen that some joints and bedding planes are preferentially followed and it can be understood why. However, it is fairly difficult to predict as until the cave is there, they cannot be studied,
But why follow one joint and not another (with the exception of knock fell caverns where it looks like every joint has been exploited ), and why do we get meanders? - back to my question about physical erosion vs. solution.
So chaotic in the sense that turbulent flow is chaotic, the water is generally flowing down hill but at the small scale it cannot be predicted which way a given "drop" or water will actually be going.
), and why do we get meanders? - back to my question about physical erosion vs. solution.So chaotic in the sense that turbulent flow is chaotic, the water is generally flowing down hill but at the small scale it cannot be predicted which way a given "drop" or water will actually be going.
graham
New member
Why follow one joint instead of another?
Because one joint is more open than the next? Because it has slightly less calcite infilling?
Why do we get meanders?
Same reason we get them in surface rivers. They are a caused by a feedback mechanism whereby more erosion and solution takes place on the outside of a curve than on the inside.
The balance between physical erosion and solution varies from place to place and I, personally, do not think that sufficient weight has been given to erosion in large caves as it is harder to measure. Having said that, the fact that the vast majority of caves are found in slightly soluble rocks - limestones - demonstrates that solution is of singular importance.
But if you think these things are wholly chaotic, take it from me that they ain't. Andy Farrant predicted the trends found in the 2009 Charterhouse extensions remarkably well. Unpublished stuff, I'm afraid.
Because one joint is more open than the next? Because it has slightly less calcite infilling?
Why do we get meanders?
Same reason we get them in surface rivers. They are a caused by a feedback mechanism whereby more erosion and solution takes place on the outside of a curve than on the inside.
The balance between physical erosion and solution varies from place to place and I, personally, do not think that sufficient weight has been given to erosion in large caves as it is harder to measure. Having said that, the fact that the vast majority of caves are found in slightly soluble rocks - limestones - demonstrates that solution is of singular importance.
But if you think these things are wholly chaotic, take it from me that they ain't. Andy Farrant predicted the trends found in the 2009 Charterhouse extensions remarkably well. Unpublished stuff, I'm afraid.
khakipuce said:The rocks on the Howgills side (north) are sandstone and the rocks on the Casterton side are limestone.
The up shot is that there is no "formula" for where a cave happens to be, it is a complex, chaotic process and they are where they are
The rocks on the west side of Barbondale and in the Howgills are Silurian mudstones - slates (impermeable) not sandstone (porous).
Caves form where there is fractured limestone, a supply of slightly acidic water (rainfall, loaded with carbon dioxide derived from decaying vegetation) at an inlet and an outlet at a lower level.
If you put some water on a perfectly flat surface (for example a piece of glass) and tip it up the water doesn't run in straight lines but has a tendency to meander its way down the glass. The same principal applies at the initial stages of cave development along the bedding planes, and the meanders we see in caves are a result of this process having continued for many thousands of years.
The BGS website shows "Coniston Group Sandstone, Siltstone and Mudstone" I don't think there is very much metamorphism.
With regard to water running down glass, I believe this is an example of chaotic behaviour (i.e. a dynamic system that is highly sensitve to initial conditions).
With regard to water running down glass, I believe this is an example of chaotic behaviour (i.e. a dynamic system that is highly sensitve to initial conditions).
