hydrology_joe wrote:Teresa wrote:hydrology_joe wrote:
The actual postulation for the increased number of anastomotic caves within the Salem is the combination of recharge through sinking streams and relatively horizontal bedding surfaces.
This contradicts your previous concept in the other thread that mechanical separations are not needed for cave formation.
No! In the previous thread I was merely correcting the incorrect notion that mechanical seperations are necessary for cave formation. Caves can form without mechanical seperations or in orientations contradictory to mechanical seperations.
I still don't believe this, no matter how many times you repeat it. So let's leave it at that. Will not believe it until someone has some data showing fluid flow dissolution by thorough wetting of a porous permeable but unfractured limestone dissolving away the rock at a X rate compared to Y rate of a similar fractured limestone. As noted before, there are no massive unfractured limestones in Missouri, though there are plenty of exceedingly tight limestones which do not form caves, including quite a number with carbonate stromatolites (middle Cambrian, and Ordovician), and a fair number of massive dolostones. Magnesium matters. It changes the dissolution kinetics.
It's quite a leap from seeing a few examples of unexplainable things to making generalizations about how all (or most) caves are formed."
Teresa wrote:hydrology_joe wrote:The floodwater injection is an interesting method for that area and could be true. Considering the geomorphic history and geologically recent downcutting (Bretz, 1965), I don't know if the host rock would have been exposed enough at the time of cave development to be subjected to floodwater injection as the Hannibal Karst Area was.
I don't know of anyone who takes the 1965 Bretz Geomorph History of Missouri very seriously any more, as it is based firmly on the pre-Strahler geomorphical theory of Wm Morris Davis, which has been pretty well debunked these days. (Just to note that hydrology_joe's cite is not to Caves of Missouri-- the whole peneplain/rejuvenation thing fails for lack of a mechanism under tectonic theory. )
Bretz's
mechanism has been pretty thoroughly debunked. Although, while the
mechanism is incorrect, the
history and
timeline are usable. [/quote]
I don't accept the history nor the timeline without the mechanism.
Teresa wrote:While the floodwater injection model might be reasonable for caves further to the north, and within the southern drainage shadow of glaciation, and/or the Missouri River valley, such is not the case in the Salem Plateau, which rises rather precipitously from the Missouri River breaks. If Spike is talking about localized groundwater flooding (say after a 5 inch rain in 24 hours) I concur, but that does not require the local host rock to be 'exposed' any more than it is presently.
Localized flood injection may be a factor, but I cannot imagine it being a regional factor. Most caves found in Missouri are exhumed by "recent" stream incision and the (limited) dating of stal in Missouri puts the regional cave ages much older than the exhumation.[/quote]
There is more stal dating out there of which you may not be aware. You may also not be aware that the researchers dating stal have an interesting selection method, depending upon what thesis they are exploring, and what access the caveowner allows to the scientist. While one obviously cannot have a stal which is older than the cave which contains it, most stal dates only go back to roughly Pleistocene time or younger. This is well within the range of usual cave ages of a few thousand to a couple of million years, and, with the exception of the glaciated areas, and outwash areas, no other significant geomorphological chages are postulated for the southern half of the state.