Aucilla River time machine
By Dr. S. David Webb
Now that our project has entered its last year of field work, I want to reveal our most important secret. We actually discovered this secret at the end of our first season, and it has sustained us through the 15 subsequent years.
In our first explorations of the Aucilla River, we discovered that the bottom consists of two very distinct types. There are shallow sections with hard limestone bottoms and, on the other hand, there are deep areas filled with dark organic sediments. These latter areas often produce rich samples of fossils. The deeper, richer areas are also usually wider, forming more or less circular patterns within the course of the river. We soon realized that these are sinkholes that were back-filled with sediments, and it is in these sinkholes, now merged with the river, that we discovered the Time Machine.
The only way to relate this stunning discovery is to start at the beginning. With only a few days remaining in our inaugural field season, Buddy Page offered to show us a very rich, very deep hole, informally known as “Booger Hole” near the middle of Half-Mile Rise. Once we adjusted to the darkness, we saw several large bones scattered about. My eyes focused on a large radius. This long bone from the forelimb is strongly bowed in mammoths. As I stared at the convex anterior face, I noticed that the outer cortex was worn almost to nothing and that it was broken just at the point of deepest wear. And as I continued to ponder the origin of that bone the TM kicked on.
As I watched, a woman came out of the darkness, picked up the radius and began scraping hides. She yelled strange sounds to a child sitting nearby. She gave a hard thrust to the radius and I saw it snap near its midpoint. The longer piece fell to the ground. I realized then that the time machine was playing this scene for those of us in “Booger Hole”. It also indicated to us that the time was more than 12,000 years before the present. The experience lasted about ten minutes. Then I realized that my SCUBA pressure gauge was about to enter the reserve zone. I was slowly carried back up to the present where the light was brighter and people spoke English.
That experience was the first of many. I began to realize that the time machine operated only in deep holes where the river encountered a standing sequence of ancient sediments. And in most such instances the TM seemed to be driven by divers’ intense interest in a specimen that invoked a particular scene from the past. I also realized that the machine gave its chronological printout based on the ratio of radioactive carbon 14 to stable carbon 12 in the sediments on location in these deep holes. As we watched the woman scraping hides, the machine evidently commuted between the past and the present, computing the difference in C14 levels. In the present it saw only 1/8 as much radioactive carbon as it saw then. It registered that two and a half half-lives of C14 had already decayed, and thus based on the half-life of 5,700 years for radioactive carbon, it calibrated that our visit was more than 12,000 years before the present.
It also occurred to me that the machine could not operate where deep sediments were absent. In such cases, few specimens could be found, and often, if there were some, they were mixtures of diverse ages, presumably giving conflicting signals. On one occasion I noted that the machine’s chronological sensor spun crazily. Only a few deep sites gave strong signals for the machine. Those of us who are fortunate to have experienced those ancient scenes, must now do our best to convey these remarkable glimpses of the lives of the first Floridians to present and future Floridians.