The Geological Society of Washington founded 1893 Wednesday, April 9th, 2025 Meeting No. 1609 Theme of the event: Rock Deformation and Tectonics Ryan McAleer, U.S. Geological Survey – Microtextures and Microchemistry in Retrograde Shear Zones: Implications for Geochronology, Deformation Mechanisms, and Rock Strength WeN-LU Zhu, University of Maryland, College Park – Effect of Partial Melt on Seismic Wave Velocity of Mantle Peridotite Emily Martin, National Air and Space Museum – Dione's Tectonic History and Evidence for a Global Subsurface Ocean Talks will be 20 minutes each with questions to follow. If anyone has any announcements or informal communications they would like to share with the society, please e-mail Vedran Lekic (ved@umd.edu<mailto:ved@umd.edu>) ahead of time. Refreshments at 7:30 p.m., formal program at 8:00 p.m. John Wesley Powell Auditorium 2170 Florida Avenue NW, Washington D.C. *** This meeting will not have an online / hybrid option *** Upcoming 2025 Spring Meetings: April 30 – Earth and Planets Laboratory, theme: M3 - Moon, Mars, Mercury May 14 – Cosmos Club