IAFI Upcoming Events Calendar

                Dr. Jeff Tepper The Cascade volcanic chain, the world’s youngest continental arc, was “born” shortly after accretion of the  Siletzia oceanic terrane ~50 My ago.   That collision, which led to formation of the Olympics, terminated the  earlier subduction system and caused a portion of the subducting Farallon slab to break off.  When Cascade  magmatism began less than 5 My later, there was a new trench located outboard of Siletzia.  In this talk I will  present a new model, based on petrology, geochronology, plate motion reconstructions, and mantle tomography,  that explains how subduction was initiated so quickly and in a setting where the slab was young and hot and in  theory too buoyant to subduct.   

    The unique landscape of the Channeled Scablands was a mystery that baffled the first geologists who visited them over 100 years ago. Finding clues, they unraveled the mystery that was unbelievable to their colleagues. After more than two decades of discovering more clues, the theory that enormous floods had carved the scabland was finally accepted by most of the scientific community.  Lloyd Stoess, President of the Palouse Falls Chapter, will take you on a journey following these two early detectives and the clues they found as well as what today's detectives and the modern tools they are using to better understand our incredible landscape.