It is time for a new picture and thread. Occasionally we hear of a sinkhole in Florida swallowing a house or draining a lake. This occurs because large parts of Florida are built upon limestone and limestone is eroded by fresh (not sea) water. In the case of Florida the fresh water is rainwater. Sinkholes only form when the limestone is above sea level. As water sinks into the lime, it dissolves it and creates a cave system. When the cave gets too close to the surface, the roof collapses creating a sinkhole. Any sediment or houses which were deposited or built on top of the cave, fall into the cave. (this is an important point for later on in this article) One can see a circular sinkhole in the very center of the photo below.



if the above coding didn’t work, then the image is at http://aquat1.ifas.ufl.edu/schardt3.jpg

Now, the formation of a cave and a sinkhole takes a long time and lots of it. The reason is that fresh water won’t dissolve very much limestone. Russ Maatman wrote:

"But a cup of water dissolves only two ten-thousands
of an ounce of limestone." Russell Maatman's book, The Impact of Evolutionary Thought: A Christian Perspective. (Dordt College Press, 1993),p 55

This means that a gallon of water will dissolve only about .09952 gm of limestone per gallon. That is a very slow rate of dissolution. So, two things are important for the formation of sinkholes—freshwater meaning the rocks were above the oceanic waters and lots of time.

So, what are we to do when we find sinkholes(also known as karsts) buried deeply in the geologic record. If they were due to the flood, then we have to have the limestone bed uplifted above the flood waters for long enough time for rain to dissolve the limestone. Below is a picture from a 3D seismic from the Gippsland basin of Australia. The circular features are sinkholes/karsts. This is buried at approximately 5600 feet deep.(Modified from Brown, 1999, p. 101)

If the sediments above and below this karsted layer were deposited by the global flood, how was there enough time to uplift the Gippsland basin, dissolve the lime, form caves and then have caves collapse forming the sink holes???

But this isn’t all that can happen with karsts, sinkholes and caves in the geologic column. On the SE edge of the Grand Canyon there is Cedar Mtn, which is formed out of Triassic strata. It is only a tiny outlier of the Triassic which once covered the entire Grand canyon area prior to the Canyon’s erosion. As one travels north from the northern rim of the Canyon, one can find the Canyon wall sediments being buried by Triassic and then the Triassic being buried by still younger strata in turn. Because of this Cedar Mtn outlier, we know that at least the Triassic strata covered the canyon and has now all been eroded away. (To move that much rock also requires considerable time).

But what does this have to do with karst sinkholes? Well, the Mississippian Redwall limestone, which is one of the cliff forming units in the Grand Canyon we find ancient sinkholes.

"The breccia pipes formed as sedimentary strata collapsed into dissolution caverns in the underlying Mississippian Redwall Limestone. Upward stoping through the upper Paleozoic and lower Mesozoic strata, involving units as high as the Triassic Chinle Formation." ~ Karen J. Wenrich and Peter W. Huntoon, "Breccia Pipes and Associated
mineralization in the Grand Canyon Region, Northern Arizona," Geology of the Grand Canyon, Northern Arizona, 28th Int. Geol. Congress, Field Trip Guide Book, (Washington: AGU, 1989), p. 212

and

"1. An extensive karst developed on the emergent Redwall surface during Late Mississippian time. The Gran Canyon breccia pipes are associated with this Mississippian karst; cavities from this karst served as nucleation points for upward stoping. The modern Yucatan karst provides an excellent analogue for Late Mississippian conditions in the
Grand Canyon." Karen J. Wenrich and Peter W. Huntoon, "Breccia Pipes and Associated mineralization in the Grand Canyon Region, Northern Arizona," Geology of the Grand Canyon, Northern Arizona, 28th Int. Geol. Congress,
Field Trip Guide Book, (Washington: AGU, 1989), p. 215

Thus, the Redwall caves didn’t collapse until after several hundred feet of sediment was deposited above them. These sediments include the Surprise Canyon formation, the Supai Group, the Hermit shale, the Coconino Sandstone, the Toroweap formation, the Kaibab Limestone and the Triassic up to at least the Triassic Chinle formation. Then the cave collapsed allowing some of the Chinle rocks to fall into the old cave in the Redwall formation. The rocks in the pipes are not soft sediment—they were hard rock when the cave collapsed. The boulders are angular and only hard rocks can sustain angular shapes.


Thus we must have the following sequence of events to explain the data:
1. Cambrian through Mississippian Redwall be deposited.
2. Redwall must be uplifted above sea water.
3. Freshwater rain must dissolve the limestone—lots of time
4. Caves must be lowered again.
5. Surprise Canyon, Supai Group, Hermit Shale, Coconino Sandstone, Toroweap group, Kaibab Limestone and Triassic up to the Chinle must be deposited.
6. Rocks must be hardened
7. The cave collapses allowing Chinle to fall into cave
8. Younger sediments which today lie only north of the Canyon were deposited.
9. Regional erosion removes thousands of cubic km of Triassic and younger rocks from Grand Canyon area

Young-earth creationism has been weighed in the balance and found wanting.