Decew Limestone
April 15, 2006 by rockwatching
This is an example of the possible cave forming rock in the area, “The Decew Limestone”. Solution caves are most likely to form in limestone and that is what I am especially interested in. you can see by the edge of this strata that some serious erosion has been taking place here. The picture was taken at a riverside constriction where floodwater is channeled just before it surges off underground. This is near a cave that is already well known to some members of the caving community. The void passes under a sleepy little rural road and waist deep in water it is possible to make a through trip in a wide and beautiful cavern.
The tunnel shape is most dependant upon it’s occurance above or below the water table. Passages beneath the water table are invariably rounded and tubular as the solution takes place in a somewhat uniform manner all around the line of flow. Above the water table the water runs freely under the influence of gravity. In those type of tunnels it is downward cutting by way of abrasion and solution that will excavate the spaces. Passage shape is often dependant upon the gradient of flow, whether there is an abrasive bedload dragged along with the water, the presence of more resistant layers within the strata and whether the water is following along a joint or bedding plane.
