Search This Blog

Texas Caves and the Flood

Copyright 2004 G.R. Morton  This can be freely distributed so long as no changes are made and no charges are made.

Karsts are due to cave collapse. Florida is a perfect example of a karsted terrain. Caves, carved out of the limestone by the movement of fresh rain water collapse and cause round sinkholes. Watching the sinkhole formation in Florida we know several things about it. It doesn�t occur every single day. We also know that it takes time to carve the caves out to the point that they will become structurally unstable. We also know that when a cave collapses, the sediment above it falls into the cave and forms a rubble. We also know that the sinkholes (karsts) are circular in shape.
Now, what are we to think when we find buried karsted terrain? Especially, what are we to think when we find these karsts very deep in the geologic record with evidence that the collapse occurred during the middle of the geologic column?
The following is taken from B. A. Hardage et al, �3-D Seismic Evidence of the Effects of Carbonate Karst Collapse on Overlying Clastic Stratigraphy and Reservoir Compartmentalization,� Proceedings of the Natural Gas Conference Emerging Technologies for the Natural Gas Industry, Dept. of Energy, 1997

The Ordovician Ellenburger Formation is a limestone and dolomite formation which covers large parts of West Texas. The dolomite is an important feature relating to the time required to form the Ellenburger as we see it today.  Dolomite is a calcium-magnesium limestone.  We will return to this important point below. The Ellenburger is also oolitic (small round carbonate grains like those we see taking months to form today in the Bahamas), and it has small sponge bioherms (see Wilson 1986, p. 98). These two items show that it took time for the Ellenburger to be deposited. It simply couldn't have been dumped into place in a couple of days.
 Within the YEC view (even within David Tyler�s view that the Cambrian and Ordovician are the only flood deposits), this formation would be deposited by the flood. Shortly after the deposition of the Ellenberger it had to be lithified.  How do we know?  Because there is an erosional unconformity at the top of the Ellenburger and below the next higher bed, the Simpson Formation.
But what is interesting, is the age of the dolomitization of the Ellenburger limestones. There are two views of dolomite, which is a calcium magnesium carbonate rather than a calcium carbonate. Some have argued that dolomite was laid down initially and other have argued that it was limestone first and then chemical reactions changed it to dolomite. There is support for this latter view in the case of the Ellenburger. Some of the limestone cobbles found in conglomerates of the Marathon fold belt in SW Texas (where the Haymond Formation is) clearly come from the Ellenburger, but they are all limestone. Wilson states:

"A related example is found in the Ordovician exotic boulders in the Marathon fold belt of West Texas. The blocks derived from the Lower Ordovician Ellenburger group are practically all limestone whereas the environmentally equivalent shelf facies is highly dolomitized. The best interpretation is that Ellenburger dolomitization occurred after the boulders were emplaced (i.e., in late Canadian and Middle Ordovician time during the formation of the widespread North American pre-Simpson unconformity)." James Lee Wilson, Carbonate Facies in Geologic History, (New York: Springer-Verlag, 1986), p. 317
Thus it appears that the Ellenburger was initially deposited as a carbonate and later changed to a dolomite.  This too would take time because it means that pore waters must flow through the rock and change the calcium carbonate to calcium-magnesium carbonate. And this must occur over a vast area--i.e. most of Texas.
Another  interesting item is that during the erosional interval,  caves were formed  in the Ellenburger.  There was enough time for the caves to form speleothems, formations of limestone formed only in caves. Loucks writes:
"The initial brecciation and fracturing are well documented to be associated with cave formation and collapse. The collapse starts at the surface contemporaneous with cavern formation and continues into the subsurface to at least 9,000 ft of burial. Cave formation is evidenced by (1) detrital cave-sediment fill, (2) Upper Ordovician to Mississippian conodonts in the sediment fill, (3) speleothems, and (4) lateral extent of brecciated pods. Paleocave collapse is the origin of most Ellenburger brecciation and fracturing. Boxwork structure and higher temperature baroque dolomite cements are evidence of thermobaric brecciation. Boxwork structure is composed of closely spaced dolomite-filled fractures on the scale of decimeters to millimeters. The host is commonly dissolved, leaving an open boxwork. The baroque dolomite cements passively fill the void spaces created by cave processes. Tectonic fractures cut host rock, lithified breccias, and lithified sediment fill. They have relatively strong directional patterns. " R. G. Loucks, "Origin of Lower Ordovician Ellenburger Group Brecciated and Fractured Reservoirs in West Texas: Paleocave, Thermobaric, Tectonic, or All of the Above?" AAPG Convention Salt Lake City, 2003.
These caves had to be formed by freshwater flow, not marine waters. Marine waters are saturated with calcium carbonate and thus can't effect a net erosion of limestones required for cave formation.  Stalactites and other dripstone speleothems simply won't form underwater. Thus, the Ellenburger would have had to have been above the waters of the global flood during the formation of the caves. This raises a question of how these beds, buried as deep as 11,000 feet today were above flood waters when they were eroded.  These caves didn�t collapse for several million years. Below is a seismic line from the above article. It show the effect of the Ellenburger ( below 1.2 seconds) cave collapse on the sediments above. These vertical collapse structures are 2500 feet tall and the karsts on the right are 500 feet or so wide. The one to the left is probably 3000 feet wide.

The sequence of events is this:  Ellenburger was deposited with enough  time for oolites and sponge bioherms to form.. Since it is impossible to deposit a hole in loose sediment, the Ellenburger had to lithify prior to the cave formation. Cobbles found in the Marathon Fold Belt show that the Ellenburger had lithified before the erosional event--something not expected in a global flood scenario. Then the Ellenburger had to have lots of fresh water run through it, carving out the caves. And there had to be time for the stalactites and stalagmites to be formed. But the caves didn�t collapse just then. The Ellenburger was then buried by younger sediment up to the Pennsylvanian aged Bend Conglomerates, of which, the Pennsylvanian Caddo is the uppermost member. These sediments then had to lithify because the cave breccia found in oil well cores taken from the collapse structures show angular cobbles of rocks from the overlying formations. Today the Caddo, in the area of this study,  is 4800 feet deep in this area and it is 2500 feet above the Ellenburger. This means that the lithification of 2500 feet of strata had to occur prior to cave collapse. Then the cave collapsed causing a major and very deep sinkhole. The red arrow at about .8 seconds shows the level at which the sinkhole ceases affecting the sedimentation.
The 3D seismic shows that the sinkholes are vertical. The maps of these two members (Caddo and beneath it the Vineyard) are shown below. They show the circular collapse sinkholes (karsts) are vertically above each other on the structural maps. These two horizons are separated by about a 1000 feet of rock. This map is the upper surface, the Caddo:

Compare this with the lower Vineyard structural map:

Everything in these karsted terrains show that much time is needed to deposit the geologic column. The questions YECs need to ask themselves.
1.How long does it take to deposit the Cambrian rocks beneath the Ellenburger?
2.How long does it take for oolites and sponge bioherms to form?
3.How long did it take for the Ellenburger to lithify?
4.How long did it take for the erosional interval to deposit the Ellenburger limestone cobbles in the Marathon Fold belt?
5.How does freshwater flow through the Ellenburger, when it is a marine deposit and was supposedly deposited by marine waters of the global flood?
6.How long does it take for stalactites and stalagmites to be formed in the Ellenburger caves? How long does it take to erode the caves?
7.How long did it take for magnesium-rich pore waters to flow through the vast area of the western half of Texas to change the calcium carbonate Ellenburger into a calcium-magnesium carbonate we see today?
8.How long did it take for the sediments above the Ellenburger up to the Caddo to lithify?
It is doubtful that creationists will have answers for this.
Now my standard questions for the YECs to ask themselves.
YECs simply do not learn of these things in the YEC propaganda literature. By only reading YEC material, the young-earther only hears that which agrees with his world view. That is an assured method to only know half of the story. The many posts I have been presenting are telling you the part of the story that AIG simply ignores because they don�t want to listen either. I have shown the pictures of these features. What do you think is telling you the truth? The pictures or AiG and ICR which never publishes pictures like these?
If one wants to see more of this on seismic data, look at page 7 of

No comments:

Post a Comment