In this episode, we dive back into the bedrock of America to reveal which state holds the crown for the oldest rocks in the U.S.! Join us as we unravel the mysteries of ancient metamorphic formations. From the Morton Gneisses in Minnesota, to the Wyoming craton out West, and ending in Upper Michigan, you'll find out what the oldest rocks are, and how we know! Hit that subscribe button, because this episode rocks! 

The paper that served as the basis for this episode is Frost, C.D., Mueller, P.A., Bickford, M.E., and Stern, R.J., 2025, USA’s oldest rock? A simple question with a complex answer: GSA Today, v. 35, p. 4–10,
https://doi.org/10.1130/GSATG613A.1.

00:00 Introduction and Episode Overview

00:50 Setting the Stage: America's Oldest Rocks

02:28 Understanding Metamorphic Rocks

05:18 The Importance of Rock Ages

09:55 Zircon and Uranium-Lead Dating

14:16 Metamorphism and Zircon Growth

22:05 Metamorphic and Igneous Rock Processes

23:32 Understanding Zircon Inheritance

24:32 Determining Rock Ages

27:21 Challenges in Identifying Rock Types

31:44 Oldest Rocks in the United States

36:52 Technological Advancements in Geochronology

42:51 Conclusion and Further Research

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