Nathaniel Klema Gordon E. Grant Carol A. Finn Pamela L. Sullivan Sarah Cooley Alex Simpson Becky Fasth Katherine Cashman Ken Ferrier Lyndsay B. Ball Daniele McKay Leif Karlstrom 2025 <p>Understanding the near-surface environment where atmospheric and solid earth processes interact, often termed the “Critical Zone,” is important for assessing resources and building resilient societies. Here, we examine a volcanic landscape in the Oregon Cascade Range, an understudied Critical Zone setting that is host to major regional water resources, pervasive silicate weathering, and significant geohazards. We leverage a bedrock age chronosequence to show that the volcanic Critical Zone undergoes a structural shift, from depth extents of &gt;1 km to meters, over timescales of ~1 My. We map an active groundwater volume comparable to major continental lakes, stored at the Cascade Range crest. This state shift makes volcanic landscape evolution a unique probe of deep coupling between Earth systems.</p> application/pdf 10.1073/pnas.2415155122 en National Academy of Sciences State shifts in the deep Critical Zone drive landscape evolution in volcanic terrains article