I’ve been to Stewart Island, off the southern tip of New Zealand, but I’m pretty sure this is the furthest south I’ve been. Cool!
We’re here in Rio Gallegos. We’ve just rendezvoused with Dr. Jay Quade, a geologist from the University of Arizona, and his wife Barbara. We’ve got two cars, a bunch of boxes of food, and plenty of gear; hopefully we’re ready for eight days in the field. Tomorrow, we’re going to drive across Patagonia toward some lakes at the eastern foot of the Andes.
Mike is a glacial geologist based at Lamont. Much of his research has focused on figuring out when the Andean ice sheets, which today are nestled in the highlands and only poke toes out toward the Patagonian plains, grew and shrank. When they grew, they extended incredible distances out of the Andes. When they shrank, they left behind moraines, tills, and tons of ground-up rock. Mike wants to know if these glaciers grew at the same time as the northern hemisphere glaciers. When New York was covered in ice, was Patagonia? Are the Southern and Northern hemispheres glaciating in or out of phase?
Jay is an expert on paleolakes. He’s also interested in reconstructing the history of the South America’s climate. He can tell when a lake was high, in the past, and if he can date that high, he can infer something about the climate system that existed at that time.
We’re headed to Lago Potrok Aike and Lago Cardiel, which are both special and strange. They’re closed-basin lakes, with no outlets, fed by rivers and streams unconnected to the glaciers that feed most of the lakes around them. Therefore, the water level is controlled almost entirely by rainfall (and seasonal snowmelt) in the surrounding watershed, with some influence from surface evaporation.
The lakes are therefore sensitive recorders of the climate system. You can’t find a much more straightforward natural system than these closed-basin lakes!
I’m tagging along with these guys to get samples for my master’s research project. I’m hoping to find dust that was deposited roughly at the time that the last ice age hit its peak, about 20,000 years ago. I’ll explain more tomorrow, but for now, I hope I’ve piqued your curiosity. Dust: way more exciting than you ever would have thought!