Exploring and Expanding the Minnesota Fossil Record

Minnesota’s fossils date back more than two billion years, with a rich and complex history. Within that time, ecosystems of three main geologic periods are very well represented within the state. From the shallow ocean waters teeming with life 450 million years ago to the coastal waters of the Age of the Dinosaurs to the frozen landscape of the Last Ice Age, this fossil record documents major transitions in life and climate. Join for an exploration of what can be found here and the current work of the Science Museum of Minnesota to expand our knowledge of ancient life in Minnesota.

Dr. Alex Hastings’ research focuses primarily on the evolution of extinct reptiles but varies widely from dinosaurs to mammoths to tiny oysters. He received his PhD from the University of Florida, worked at Georgia Southern University, did a research fellowship at Martin Luther University in Halle, Germany, was the Assistant Curator of Paleontology at the Virginia Museum of Natural History and has been the Fitzpatrick Chair of Paleontology at the Science Museum of Minnesota since 2018.

How Ancient Iron-Rich Rocks Tell the Story of Past Oceans

Minnesota’s iron-rich rocks preserve geochemical information about what seawater was like billions of years ago. To interpret this record however, we must peel back the layers of time by reading mineral reactions that occurred after the rock formed. High-spatial resolution geochemical tools allow us to measure the elemental and isotopic composition of single mineral phases, while preserving textural relationships. Preservation of cross-cutting relationships, micro-banding, grain size, shape, and cement volumes allow us to build a geochemical history of each sample, where we can separate out secondary changes to reveal primary compositions. Because these iron-rich rocks originally form through precipitation from seawater, their primary composition informs our interpretation of how oceans evolved over time, and what that might mean for early life.

Dr. Latisha Brengman is an Assistant Professor at the University of Minnesota Duluth and runs the Precambrian processes lab there. Brengman and her research team work to solve Precambrian problems at the intersection of sedimentary and hydrothermal processes, using tools that span the macro- to micro-scale. The team’s main research projects focus on deciphering the record after sedimentary rocks form in order to assess the preservation potential of primary geochemical signatures that link to ancient ocean chemistry. They specialize in high spatial resolution tools and methodologies that focus on sample preservation. For more information about her projects visit her research website: http://www.latishabrengman.com/

Minnesota Mineral Club Member Ben Chorn presents on Montana Moss Agates, including composition, locations, and tips on finding them.

Ben is a professional geologist who grew up in the Twin Cities. He studied geology and business at Rocky Mountain College, and received a master's degree in geology from the University of Minnesota Duluth. Ben lived a total of 7 years in Montana and frequently returns for rockhounding.