Monthly Presentations

The Central Oregon Geoscience Society holds regularly scheduled monthly presentations on the 4th Tuesday of each month, from September to November, and from January to May. All presentations are free and open to the public.


We have returned to in-person presentations!

Please join us at Bridge 99 Brewery:

63063 Layton Avenue, Bend

5:30 pm social hour

7:00 pm presentation

Please join us for the social hour before the presentation -- all are welcome! 

Presentations are also live-streamed through Zoom. Please see the presentation details for Zoom registration links. Zoom presentations are recorded whenever possible, please see the list of past presentations to watch recordings of past talks.


Visiting Scholar Presentations

Visiting Scholar presentations are scheduled during various times outside the regular monthly meeting schedule. Please check the schedule below for updates, or join the COGS email list for updates. To join the email list, go to the Join us page.



Upcoming Presentations

    • 24 Jan 2023
    • 7:00 PM
    • Online and in-person at Bridge 99 Brewery

    Lisa Tauxe

    University of California San Diego, Scripps Institution of Oceanography




    William Gilbert, the physician to Queen Elizabeth I, realized back in 1600 that the Earth's magnetic field was very much like one that would be produced by a bar magnet in the center of the Earth aligned with the spin axis. This is the heart of what is known as the 'geocentric axial dipole hypothesis', or GAD, and is how we know continents have drifted over the billions of years of Earth's history. Given a GAD field, if we know a field direction at a particular location at a particular age, we can predict where the axis of the centered dipole intersects the surface of the Earth (a paleomagnetic pole position) and conversely, we can use a particular pole and predict the magnetic field direction. The GAD hypothesis has been validated for at least the last billion years or so. 

    I am interested not only in the ancient directions of Earth's magnetic field, but in the strength of the magnetic field as well. It turns out that while the directions recovered from ancient rocks are consistent with a GAD field, the strengths are not. Why not?  Is this a failure of the method we use to estimate ancient field strengths? Is this because we have under-sampled a highly variable field? Or is this a failure of the GAD hypothesis itself? The answers may lie beneath our feet in Oregon in the abundant volcanic deposits all around us.  


    We have returned to in-person presentations!

    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.

    • 28 Feb 2023
    • 7:00 PM
    • Online and in-person at Bridge 99 Brewery

    Adrian Broz

    Purdue University

    University of Oregon





    Decades of space exploration have shown that the surface of Mars billions of years ago was a habitable place that had abundant liquid water. The formation of soil from precipitation-driven weathering of volcanic ash and tuff may have been a common process early in the planet's history. Ancient soils on Earth preserve biosignatures (past signs of life) and hold a record of the climate when they formed, and thus Martian paleosols are considered high-priority targets for biosignature investigation and sample return to Earth.

    This talk will explore the factors that lead to enhanced preservation of biosignatures in paleosols from throughout Earth's geological record. As a case study, we use eastern Oregon's "Painted Hills" as a Mars-analog location to determine if Mars-rover-like instruments are suitable for examining the mineralogy, diagenesis and organic content of ancient soils. Please join us in exploring ancient soils of Earth and Mars!

    Adrian Broz is the Mars 2020 Perseverance Rover postdoctoral scientist at Purdue University, and works in the Soil-Plant-Atmosphere Lab at the University of Oregon.


    Potential paleosols at Mawrth Vallis, Mars (left) and paleosols at the Painted Hills, Oregon (right)


    We have returned to in-person presentations!

    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.

    • 28 Mar 2023
    • 7:00 PM
    • Online and in-person at Bridge 99 Brewery

    Scott Bennett

    U.S. Geological Survey








    The Mount Hood fault zone is a N-trending, ~55 km-long zone of active faulting along the western margin of the High Cascades graben at the crest of the Oregon Cascade Range. Recent geologic mapping, fault scarp analysis, and a hand-dug paleoseismic trench on the Gate Creek fault, the northernmost segment of the Mount Hood fault zone, indicate the most recent earthquake occurred between AD 1363 and AD 1495. These dates overlap with tree-ring dates between AD 1446 and AD 1447 from trees drowned when the nearby Bonneville landslide blocked the Columbia River and impounded a lake 75 meters deep. The impounded lake then partly breached the landslide dam, causing downstream flooding in the Portland basin prior to AD 1479–1482.

    Ground motion modeling of a magnitude ~7 earthquake along the Mount Hood fault zone suggests strong shaking at Table Mountain, the headscarp of the Bonneville landslide ~15 km west of the Mount Hood fault zone, could have initiated the landslide. Thus, it is possible that an earthquake in the 15th century along the Mount Hood fault zone could have triggered a cascade of hazards, including the earthquake itself, an earthquake-triggered landslide, and then a flood from breaching of the landslide dam.



    We have returned to in-person presentations!

    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.

    • 25 Apr 2023
    • 7:00 PM
    • Online and in-person at Bridge 99 Brewery

    Nick Famoso

    National Park Service







    It is clear that ecosystems are devastated after a volcanic eruption coats the landscape with a layer of ash; however, the ecological recovery of mammalian communities after eruptions is poorly understood. Volcanic eruptions vary with magnitude and type and only a fraction of them have been analyzed for effects on mammalian communities. In this talk we will explore how mammalian species change across volcanic boundaries by looking at three volcanic eruptions: the 1980 Mount St. Helens eruption sheds light on short term recovery after a moderate sized eruption; the 1914-1917 Mount Lassen eruption permits an analysis of long-term impacts from a relatively small eruption; and the Picture Gorge Ignimbrite (28.7 Ma) within the Turtle Cove Member of the John Day Formation was a supervolcanic eruption associated with the Yellowstone hotspot.




    We have returned to in-person presentations!

    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.

    • 23 May 2023
    • 7:00 PM
    • Online and in-person at Bridge 99 Brewery

    Sam Hopkins

    University of Oregon










    The ongoing human-mediated changes to climate and habitat are taking us into unknown territory, and there is a real need to understand what we can expect in ecosystem responses. The fossil record provides some important evidence to allow us to forecast ecosystem responses to environmental change, and small mammals in particular offer sensitive barometers of ecological change. Oregon’s rich record of fossil rodents over the last 30 million years gives us an opportunity to understand how these smallest mammalian residents react to the dynamic Oregon landscape, and to guess at how future ecosystem change might drive further faunal change.


    We have returned to in-person presentations!

    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.

Past Presentations

22 Nov 2022 The development of the science of geology and the growth of the railroad industry: How geology played a significant role in railroads of the Pacific Northwest
25 Oct 2022 The Rock Bottom of Antarctica’s Food Chain
27 Sep 2022 Paleoseismic investigations of Quaternary active faults in the forearc and backarc of the central Pacific Northwest
22 Sep 2022 Evidence of humans in North America during the Last Glacial Maximum
28 Jun 2022 Volcanoes! Travelogue and Science of Two Volcanic Arcs
24 May 2022 Encountering the Unexpected in Pacific Northwest Geology
26 Apr 2022 When Magmas Meet High-Tech Metals: What Can the Mountain Pass Rare Earth Element Deposit Bring to the Future?
22 Mar 2022 Newberry Volcano Geothermal Projects, Past and Future
22 Feb 2022 From maar craters to cinder cones: Understanding Oregon's small, but most common, volcanoes
25 Jan 2022 Wildfire and Debris Flows
23 Nov 2021 Tectonic evolution of the Cascadia margin in southwest Oregon during the past 55 million years
26 Oct 2021 Evaluation of slip history and Holocene activity on faults in the Strawberry Mountains
28 Sep 2021 Timing and controls on growth of the Oregon Basin and Range Province
25 May 2021 I Date Rocks: A Geochronology Love Story
27 Apr 2021 Water in the Deschutes Basin: 2020 Hindsight – What Happened?
23 Mar 2021 The fragmented death of the Farallon Plate
23 Feb 2021 Our Vanishing Glaciers, Part II
26 Jan 2021 The Next Great Cascadia Earthquake - How did we get here?
24 Nov 2020 What lies under recently active Cascades volcanoes?
27 Oct 2020 Mapping the Magmatic Pathways Beneath Volcanoes from Newberry, Oregon to Santorini, Greece
22 Sep 2020 Red Rocks from Earth to Mars
25 Jun 2020 Extinction: Using catastrophic events to construct the geologic timeline
26 May 2020 The history and science of glacier change in the western US and a peek into their future
28 Apr 2020 Volcanoes in Our Backyard: Understanding and Mitigating Volcano Hazards in Central Oregon
24 Mar 2020 I Date Rocks: A Geochronology Love Story
25 Feb 2020 Mountains, Earthquakes, and Landslides: Using Lasers to Peer Behind Cascadia's Green Veil
28 Jan 2020 Three Newly Discovered Fault Systems in Oregon
26 Nov 2019 Oregon's Checkered Past
22 Oct 2019 The Other Flood: Ice-age Bonneville Flood on the Snake River
24 Sep 2019 Tectonic History of the Coos Bay Basin and its Relationship to Pacific Northwest ‘Siletzia’ Tectonics
10 Aug 2019 Newberry Volcano: A sleeping giant with two bubbling lakes
28 May 2019 Holocene Glacial and Paleoclimate Reconstructions in the North Cascades, Washington
23 Apr 2019 A new look at “old” tuffs from Newberry Volcano: Evidence for dynamic magmatic processes at a geologic crossroads in central Oregon
26 Mar 2019 Kīlauea's 2018 Fissure Eruption – Chronology, Processes, and Impacts of Kilauea's Largest Eruption in 200 Years
26 Feb 2019 Mountains, Earthquakes, and Landslides: Using Lasers to Peer Behind Cascadia's Green Veil
22 Jan 2019 The High Lava Plains of Oregon: Volcanic and Tectonic Connection between Yellowstone and the Cascades
27 Nov 2018 Groundwater hydrology and groundwater-dependent ecosystems of central Oregon
23 Oct 2018 The Crooked River Caldera
25 Sep 2018 Assembling the Northwest: A roadside view of Oregon and Washington geology
16 Jul 2018 Oregon's volcanoes: What have we learned from global advances in volcanology over the past decade?
22 May 2018 Oblique subduction, rotating crustal blocks, and the active tectonics of the Pacific Northwest
24 Apr 2018 Mount Hood: Confessions of an interesting Boring volcano
27 Mar 2018 Geothermal Exploration at Newberry Volcano

Central Oregon Geoscience Society

Email: COGeoSoc@gmail.com
P.O. Box 2154,  Bend, Oregon 97709

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