Josh: I'll buy your explanation for Jim Conrad's road cut, but my mystery rocks are entirely different. Tell me what you think: (Photo not shown, email me and I will send it. Is there any way to post a resized photo on Texas caver? I see that others have occasionally posted photos. I tried but failed) These mystery rocks occur in broad shallow pans west of Cancun near the airport that look superficially like dolinas, actually more like the wet "prairies" here in Florida. It is only the top layer that is hard and has inclusions. Beneath that is standard yucatecan crumbly white limestone. There were occasional solution holes in the pans but no real cenotes. You are not looking at the top or bottom of one of the flat rocks, but rather a broken chunk, so don't infer any particular orientation. I would have supposed that this was some form of hardpan, or perhaps chertification as you can see in the upper left rock, but the lack of inclusions further down and the immediate change in hardness tells me this is a separate formation. The surface rocks in the yucatan are generally harder than the rocks further down, which is part of the reason why the cenotes almost always bell out as they go down. That is normal, but when I looked carefully at these specific rocks in the pans I discovered something very strange. The pan rocks were in solid (though broken) sheets averaging about 8" thick, and were composed of a matrix of hard creamy white fossiliferous limestone in which were numerous broken jagged chunks of what looks like dark gray dolomite to me, but I could be wrong about that. The chunks are clastic, not rounded and weathered, and rarely touch each other. It looks like cake mix with chunky treats mixed in. What could cause such a thing? It seems obvious to me that a huge disaster was required to turn the limestone matrix into soup with jagged chunks. A conventional flood would sort the inclusions differently and round them too.
The Yucatan is generally a wretched dry place covered with tangled scrub that has been abused by people and fire for thousands of years. The only places that are botanically interesting were these pans, which were alternately flooded then burned each year resulting in an open savanna landscape with occasional "Logwood" trees (Haematoxylum campechianum is a cool twisted small tree which yields a purple dye, and as a result was long sought in days of yore). The reason I discovered all this is because once upon a time I built a monstrous waterfall at a hideous resort in Cancun. Most of the limestone in the Yucatan is worthless white chalky crap unworthy of working with, but in certain areas, such as near the Cancun airport, there were these botanically and geologically interesting "pans" in which the surface limestone was much harder, flatter, and more useful. So in I went with a whole tribe of Mayans to harvest the stone by hand. On day one I did something extra stupid. Bigger rocks are always better, especially if someone else is lifting them, so I pointed at a big slab about the size of a dining room table. The Mayans said "No way Jose, too big!" But I insisted, so I said, all you little guys get on one end and I'll take the other and we'll put it in the truck. With great effort we lifted it up and into the truck, but in doing so I got 3/4 of an inch shorter as my cervical vertebra collapsed. I've always been short, so getting permanently shorter and being in pain for years didn't help! After that we collected smaller rocks in the 100-150 lbs range, each one of which was pried up in the scrub jungle, loaded onto the back of an individual Indian, carried to the truck, lifted in, taken to the site, unloaded, picked up again to reload on the back of another Indian, carried through the already occupied resort, then lifted up the scaffolding by hand to be set. We even carried in a sixty foot tall royal palm that weighed perhaps six tons. I was much impressed by the fact that the Mayans were invariably smarter than any of the tourists, who were so dumb that after months I had seen only one reading a book so I went over to see what he was reading and it was a Reader's digest. The only smart Gringos I met the whole time I was there were two professional "closers" who would fly in, ply the prospective chump with drinks and cocaine, then threaten to kill them if they didn't sign the timeshare contract. Meanwhile back in the village otherwise illiterate Mayan kids were learning computer aided design by candlelight. Their skill and craftsmanship were extraordinary. The boss was an edjumacated Mexican aristocrat. The site was gigantic, about an 1/8 of a mile across, yet his tolerance for mistakes was only 1/8" regardless of whether the issue was a window frame or the entire site, but the Mayans never made mistakes. Everything was perfect despite that fact that the entire place was a worthless piece of shit. The monstrosity that I created can be seen _here_ (http://www.environmentaldesigns.org/Projects%20by%20type/lightscapes.html) , and _here_ (http://www.environmentaldesigns.org/Projects%20by%20type/lightscapes.html) . And to think that I remember Cancun when there wasn't anything there, not even a palapa selling cokes! Sleazeweazel
