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My Blog on Global Warming issues http://themigrantmind.blogspot.com/
by Glenn R. Morton
Copyright 2003. This may be freely distributed, posted, or linked to, so long as no changes are made to the page and no monetary charges made for viewing.
http://home.entouch.net/dmd/hardgrounds.htm
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In March of 1984, I was sent on an AAPG field trip to look at carbonates in South Texas. The area we examined has at least 15,000 feet of sedimentary rock below it. Global flood advocates claim that all of this sediment was deposited by Noah's catastrophe. The rocks we saw presented a serious challenge to that view, a view which at that time, I held.
One of the sites was along Bear Creek where we saw a series of hardgrounds. A hard ground is a slowly deposited carbonate which is very hard and resistant to erosion, which is why they form ledges along the banks of this creek. What happens is that the land subsides, and a softer form of carbonate is deposited, which then fills the void caused by the sea level drop. As the carbonate gets near the sea surface, the rate of deposition drops and the hardground carbonate is deposited. The fuzzy photo below is from a slide I took which shows the hardground limestone ledges jutting out from the cliff face.
But that doesn't stop biological activity. In the shallow waters, especially when the softer carbonates were being deposited, dinosaurs walked in search of food. Below is a photo of a dinosaur track which walks in the softer sediment above the lowest observed hardground. If this was during the middle of the global flood, at a point in the flood where ,There are creatures, like clionid sponges, which burrow into carbonate rocks.
But an even more interesting record of the time it takes for this section to be deposited comes from the nature of the biologic activity seen on the hardgrounds. Each hardground is highly burrowed by animal life. I believe these animals are clionid sponges which eat shell material as part of their search for food. Below is a rock I brought back from this sight. You can clearly see the burrows, and the fact that the waters were very shallow is shown in the crack which was filled by an evaporative mineral, celestite.
There are six ledges along this creek bank, each has burrows and desiccation cracks just like this. In the rocks in between these hardground ledges are burrows of other animals and dinosaur tracks. It takes time for burrowers to burrow, and it takes time for dinosaurs to walk. Given that there was already 15,000 feet of sediment beneath this site, and there are more than 50,000 feet of total sediment which lie stratigraphically above rocks of this age in the Gulf of Mexico, just a three hundred miles to the east. If all these vast thicknesses of rock are due to the flood, then this site is smack in the middle of the raging flood. So what were the dinosaurs doing walking around when vast quantities of sediment were falling on their heads? And how fast must one believe that burrowers can burrow? Young earth creationists have much to explain and in two hundred years of geological science, they keep getting further and further behind.