 The research that has been done in the Vias Caldera over the last 60 years has made major contributions to our understanding of how geologic systems work. In 2004, scientists drilled a core sample from the ancient lake bed of the Via Grande. Analysis of this core gives us a window into past climate cycles in the Vias Caldera. The reason that we wanted to drill here is that there's a really interesting interplay between the volcanism here in the Caldera and the lakes that formed. So following the formation of the Caldera, there were a series of rhyolite domes that formed in the moat. And the one that's significant here is South Mountain behind us here that formed 550,000 years ago and it blocked the drainage out of the Via Grande here. So instead of meadows and streams like you see here today, it would have ponded up with water and filled up with sediment. The reason this is significant is because most lakes that you study go back maybe 10, 20, 30,000 years if you're lucky. This one is kind of unique because it captures a snapshot of time from 550,000 years ago to about 350,000 years ago. And I can count on one hand the number of lake deposits in the world that go back that far with such a high resolution. Yeah, so lake sediments are really important for recording terrestrial climate because over time as the lake fills in and sediments accumulate, things that are in the watershed around the lake at the time actually pile up in those sediments. For example, pollen from the trees that are around us here wash into the lake and that gives you a record of what the vegetation was like. So as climate changes, the vegetation changes, and then the pollen actually change in the lake. So we get a nice record that way. Other things, we have charcoal washing into the lake that tells us something about the forest fire frequency and intensity. So initially what we did with the sediment was to look at it and say, what's here? And what we found were mostly lake muds with some silty material in it. Parts of the lake core were actually very nicely laminated, which indicates it's a deep lake. And there are parts of the sediment where there are mud cracks that indicate that the lake basin pretty much dried out and that indicates a very severe dry climate, which is actually quite unusual. So there's a very significant correlation between climate that's warm or warmer than today and what we termed megadroughts where you have periods of either centuries to thousands of years of dry climate. So other information that we were able to get from the core that's really, really helpful is that we were able to look at the structure of what past interglacials looked like. So in the modern last 10 to 11,000 years we've been in a rather long extended interglacial. And one of the questions that paleoclimatologists, modern climatologists would like to address is what is climate going to look like in the next 10 to 20,000 years without any human influence? Well it turns out that one of the interglacials that we looked at in the core, it's called marine isotope stage 11, that won't mean much to most folks, but it's a period about 430,000 years to about 400,000 years ago. It turns out that that interval is very similar to the modern interval in terms of the way that the Earth's orbit occurred and many other climate forcing factors. So it's kind of like a natural analogue or a natural laboratory, if you will, for what climate would look like over the next 10 to 20,000 years in the absence of human influence, if you will. And one of the things it tells us is that given that we're about 10 to 11,000 years past the last gasp of the last glacial, we should be heading back into a cooler, and for New Mexico, a wetter interval. Instead what we're seeing is that climate is becoming warmer and especially with the drought that we've seen in the last few years in the Southwest, it's becoming drier. So this record seems to suggest that the natural climate wants to head one way and what we're seeing is it's heading the other way. And the most likely influence for that is the anthropogenic addition of carbon dioxide to the atmosphere.