Upcoming Presentations

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• How, Why and Where Earth Melts

  • When
    27 Feb 2024
  •  
    5:30 PM
  • Location
    Online and in-person at Bridge 99 Brewery

  Dana Johntson
  

  University of Oregon
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  5:30 pm social hour

  7:00 pm presentation

  
  

  A common misconception is that magmatism within our planet results from a thermal anomaly of some sort, causing a local perturbation in the geotherm. While this is sometimes the case, the vast majority of magmatic activity in fact results from decompression of hot rocks or lowering their solidus temperature through the introduction of fluxing agents, principally H₂O. The former dominates at mid-ocean ridges, oceanic and continental hot spots and continental rifts while the latter dominates at subduction zones. Much of our knowledge of these processes derives from experimental petrologic studies at elevated pressures and I will show how such investigations shed light on these mechanisms through which our planet differentiates.

  
  

  
  

  Please join us at Bridge 99 Brewery:

  63063 Layton Avenue, Bend

  5:30 pm social hour

  7:00 pm presentation

  COGS talk are free and open to the public -- all are welcome! Please join us for the social hour before the presentation.
  
  All presentations are also live-streamed through Zoom. There will be a registration link at the top of this page as we get closer to the date of this presentation.

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• From the Last Glacial Maximum to Present: New Chronologies for Oregon’s Cascade Ice Cap and Glaciers

  • When
    28 May 2024
  •  
    5:30 PM
  • Location
    Online and in-person at Bridge 99 Brewery

  

  Anders Carlson
  

  Oregon Glaciers Institute
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  
  

  5:30 pm social hour

  7:00 pm presentation

  
  

  During the last ice age an ice cap covered much of the Oregon Cascade crest, with a north-south length roughly between that of the modern Northern and Southern Patagonia ice caps. Oregon’s ice cap stands out from other late Pleistocene ice bodies in the western United States in that its deglacial history is largely unknown. Here, we will present new Helium-3 surface exposure ages for the ice cap collected from the Three Fingered Jack and Middle Sister regions. These ages will directly date when it retreated from its last glacial maximum extent and then paused to deposit moraines close to late Holocene/historical moraines. This new chronology will allow us to relate ice-cap change to regional climate change as recorded in marine and cave temperature records. We will also have new Helium-3 ages for potential prehistoric late-Holocene moraines just outboard of historic moraines from Hayden Glacier on Middle Sister and Eliot Glacier on Mount Hood. In sum, these new ages will expand the record of cryospheric change in Oregon from less than the last 150 years, to likely more than the last 20,000 years.

  
  

  
  

  
  

  Please join us at Bridge 99 Brewery:

  63063 Layton Avenue, Bend

  5:30 pm social hour

  7:00 pm presentation

  COGS talk are free and open to the public -- all are welcome! Please join us for the social hour before the presentation.
  
  All presentations are also live-streamed through Zoom. There will be a registration link at the top of this page as we get closer to the date of this presentation.

  Show details