Ian Winkelstern

Clumped Isotopes of Bonneville and Glacial Material

Travel back in time to about 15,000 years ago. Everything around you looks much the same. There aren't any buildings, roads, or any other signs of civilization, but you see the familiar landmarks that tell you that you're still on the Wasatch front. There's just one tiny difference. You're currently floating in a massive lake that stretches as far as you can see in every direction. Welcome to Lake Bonneville!

The February 20, 2025 seminar, hosted by the Department of Geological Sciences, featured guest speaker Dr. Ian Winkelstern, an assistant professor at Grand Valley State University, Michigan. He received a Ph.D. from the University of Michigan in Earth and Environmental Sciences, an M.S. from the University of North Carolina at Chapel Hill in Geological Sciences, and a B.S. from the University of Michigan in Geological Sciences. He is currently an assistant professor at Grand Valley University and specializes in carbonate sedimentology and paleoclimatology. His presentation for the seminar was titled "Linking Modern Lakes to Ancient Lake Bonneville with Stable Isotopes."

Although modern science hasn't figured out how to literally travel through time, it has allowed us to gain a better understanding of what the world might have been like in the past. Dr. Winkelstern explained some of the methods that he and his team use to look at geological formations and the processes by which they were created. Using carbonate and water isotopes, scientists like Winkelstern can infer what ancient temperature, evaporation and precipitation rates might have been. In addition, the water chemistry of snow and glacial melt and groundwater can be deduced and compared to modern-day bodies of water.

Dr. Winkelstern talked about two projects where these methods were used. The first was at a small lake in Michigan called Ore Lake. He and his students experimented on a theory proposed in a previous study that examined the formation of small pebble-like rocks called pisoids and the unusual rings or concentrated bands that were found inside. The original study postulated that the rings were formed due to differences in temperature in the changing seasons from year to year, but Winkelstern and the team thought it was strange. Using the modern-day analysis techniques, the team found that the unique formations of the concentrated bands were not caused by changing seasonal temperatures but instead from changes in precipitation in the summer season.

The next project examined the paleohydrology of Utah's own Lake Bonneville. This lake was once a body of water comparable in size to Lake Michigan, covering most of northern Utah and extended into Nevada and Idaho, and reaching approximately 20,000 square miles in size and nearly 1,000 feet of depth at its peak. Due to the changing climate, the Great Salt Lake is nearly all that remains of Lake Bonneville. Dr. Winkelstern wanted to determine the temperature of the climate at the time when Lake Bonneville was at its maximum extent, as well as what other conditions would be needed to sustain such a large body of water. By examining the data of triple oxygen isotopes found in fossils in the area, he was able to conclude that Lake Bonneville was much cooler and fresher than the Great Salt Lake. This means that there was less evaporation occurring and therefore a greater capacity to grow to the size that it did. Lake Bonneville was remarkably similar to Lake Michigan in many regards, which means that by learning more about this lake, Dr. Winkelstern and others can apply their knowledge to help in ensuring the preservation of our Great Lakes.

As we progress in our knowledge of the world around us, we are more capable of making it a better place. That is the mission of Dr. Winklestern and other geoscientists. The knowledge gained by studying Lake Bonneville is just one example of this ground-breaking work. By delving into our past, we come to better understand the world that we live in, one isotope at a time.