Today I traveled with Gary and Carol in search of stalagmites in Indiana Caverns and nearby cave passages. Because I need to analyze the stalagmites in a laboratory, I have to physically remove my stalagmite samples from the cave. Typically, removing or disturbing cave formations is illegal and extremely frowned upon. However, an exception is made here for scientific purposes. The knowledge gained from the removal of a select few formations is viewed as greater than the minor disturbance to the cave. Collection of formations is designed to be of as little impact to the cave environment and aesthetics as possible.
We traveled past the boat tour to a rarely visited room that had stalagmites along with other formations like soda straws and draperies. The best stalagmites for climate records are symmetrical and somewhat squat, because this means that their growth was likely steady over a long time. We found two stalagmites that fit my criteria and removed them with a hammer and chisel. I also collected a sample of the water dripping from the ceiling for analysis.
I will take these two stalagmites back to the University of Georgia for further work. In my lab, I’ll gather as much information as I can from them. First we have to figure out how old the stalagmites are. We are able to date the stalagmites by comparing two radioactive elements (uranium and thorium) contained in the stalagmites. Sometimes, we can date stalagmites to 500,000 years old! However, it is more likely the two stalagmites we collected are less than 100,000 years old. Once we know how old the stalagmites are, I begin to gather climate information through chemical testing and looking at the stalagmites under a microscope. I can even get estimates of changes in the plant density above the cave by looking at the stalagmites under ultraviolet light! Eventually, I’ll gather all my information taken from the stalagmites and combine it into a single record tracking how the climate changed for southern Indiana.
This is but one part of a larger project I am working on. I have samples from two other Indiana caves farther north. Indiana is a special place because the Ice Age glaciers came farther south here than almost anywhere else in the Northern Hemisphere. This means Indiana has seen radical changes in climate over the past 100,000+ years. With these multiple cave records, I hope to better understand how Indiana’s climate has reacted to the advance and retreat of glaciers in the Ice Age, as well as understand potential changes in the future. Indiana Caverns has the potential to be an extremely important source of information about the past climate and environment of Indiana, and I am both grateful for this opportunity and looking forward to working again with everyone here!