1-1-1-1-1-1-1-1-1-1-1-1-1-1 From: Jon Fink <jonfink@xxxxxxx> Come join GSA Field Trip #406 to see some of the best-exposed dike-fed silicic domes in the world! The trip, titled "Silicic Lava Domes of the Cascades of Oregon and Northern California," led by Jonathan Fink and Steven Anderson, runs from Thursday to Sunday, October 7-10, before the Annual GSA Meeting in Portland. This slightly modified version of a trip that we ran for the 2017 IAVCEI conference will visit Newberry, South Sister, and Medicine Lake Volcanoes in Central Oregon and Northern California. These are among the best such exposures anywhere, and we have studied them for over 40 years. On Day 1, we leave Portland, stop at Timberline Lodge on Mount Hood, visit Newberry Caldera and the Big Obsidian Flow, and spend the night in Bend. On Day 2 we climb partway up South Sister to look at the Devil's Hill domes, with an optional climb to the summit, and then drive to Klamath Falls, Oregon where we spend nights 2 and 3. On Day 3 and the morning of Day 4 we will visit Medicine Lake Volcano, checking out Glass Mountain, Little Glass Mountain, Medicine Lake Dacite Flow, and uniquely well-exposed ground cracks that formed over a dike that fed the Crater Glass Flows. The exposures of explosion pits and contorted glassy and pumiceous textures in the quarry on the south side of Glass Mountain are particularly spectacular, as are the crease structures on the surface of Medicine Lake Dacite Flow. On the afternoon of Day 4, we will drive back to Portland. A link to the 2017 Field Trip Guide, published by the USGS, can be found here <https://urldefense.com/v3/__https://www.dropbox.com/s/ftqlaunyufh67yk/Fink*20*26*20Anderson*202017*20Emplacement*20of*20Holocone*20siilicic*20lava*20flow*20and*20domes*20USGS*20Sci*20Inv*20Repts*202017-5022-I.pdf?dl=0__;JSUlJSUlJSUlJSUlJSUlJSU!!IKRxdwAv5BmarQ!IvBxEvKEZxzh_X2OvPM8x7Wg_0aMSaAFWywXpc3cLBFCyg04D8HvRtILPPicJ1s$> : The cost of $875 covers transportation, food, and three nights' lodging. Space is limited (9 openings remain). Register here: https://urldefense.com/v3/__https://community.geosociety.org/gsa2021/program/field__;!!IKRxdwAv5BmarQ!OKfGroBIhOZQMrbYpIrIkbT8cTMs4TRscC3o3wNo2aEn4YnTeIep3I01Rs1FGxM$ <https://urldefense.com/v3/__https://community.geosociety.org/gsa2021/program/field__;!!IKRxdwAv5BmarQ!IvBxEvKEZxzh_X2OvPM8x7Wg_0aMSaAFWywXpc3cLBFCyg04D8HvRtILtzwF1AA$> Contact jon.fink@xxxxxxx with any questions. 1-1-1-1-1-1-1-1-1-1-1-1-1-1 ------------------------------ End of Volcano Digest - 11 Aug 2021 to 16 Aug 2021 (#2021-75) *************************************************************
