Geology of Central Oregon: The Crooked River Caldera 

Great information, very well presented, easy to understand for non geologists

Oregon is such a geologic playground. So much to see and learn about. Carrie, thank you for describing the story of the Crooked River caldera. Please keep these virtual presentations on Oregon geology coming. You and all the Geology professionals are such a treasure to our beautiful state of Oregon.

Fabulous talk! Exciting presentation and so informative. Thank you.

GREAT descriptions of local geology features.

Great presentation, love geology. Thank you.

Hello from Texas...love the land and the geology of Oregon....and anyone that respects others...

This is great. I’ve been fascinated with this area for years. I was able to read one thesis on the crooked river gorge from the 1970s and was left with more questions than answers. Thank you

Please tell Ms Gordon we found her presentation very informative and inspiring to understand geology more. We love her enthusiasm and lively presentation style. We watched it last night and today we are exploring the prineville area wishing she was driving along with us.

Absolutely phenomenal loved all that she had to say just going up there today seeing the area and now listening to the stories about it and is fantastic thank you thank you thank you

This is a great talk. Thanks. To add to what was said regarding the question about the timeframe for tuffs to harden, as the speaker said there are different kinds of tuffs. Regular tuffs are soft and friable, and “welded tuffs” (also called ignimbrites, are hard and cliff-forming. Theses welded tuffs become welded in a matter of minutes, as they are deposited in 800°C pyroclastic density flows. The weight of the deposit itself also helps to compress them into harder rocks, but the main thing is that they are just erupted hotter than other tuffs, and as pyroclastic density flows, or ash flows, as opposed to ash-fall tuffs, which are not hot enough to weld generally, being cooled in the atmosphere while they fall. So the answer is, the hard “welded tuffs” become hard almost as soon as they are deposited, in a geological instant. The soft ones mostly never do, and as the speaker said, they get eroded much easier. There is one caveat here though, which is the looser tuffs can also become “silicified” over a much longer time, by the percolation of groundwater and hydrothermal water through them, which dissolves silica and other minerals in the rocks and redeposits it between the loose tuff grains, strengthening the rock. But the rocks that people climb on at smith rock were “welded” near instantaneously.

Is the Crooked River caldera deposits (rhyolite) tied chemically to the Yellowstone hot spot?

Are there any active calderas? Of course there are! Crater Lake for one. Long Valley. Valles. Yellowstone. Aniakchak. Campi Flegri. Kilauea. Mauna Loa. Tambora. Krakatau. Hunga Tonga Hunga Ha'apai. Ta'al. Pinatubo. Santorini. Aira. Bardurbunga. All have calderas. The mistake made here is implying "caldera" is a type of volcano. It isn't. Both explosive and effusive caldera exist and all they are is a landform related to the eruption of a large volume of magma followed by collapse of roof of the magma chamber the eruptive products came from.

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Geobiology is the new thing, the study of flesh turned to stone what most of the earth is, with lava mixed in

Can't find Erchico or Irchico (sp?) Mts. "east of here" on the map. (c. 11:00 ) Anybody?

if you find a job you like you will get very good at it ,you may even get passionate ,she is fantastic thank you

Not sunflowers but Brown Eyed Susans in Central Oregon

This lecture must be aimed at 5 year olds. My bad. I thought I was going to hear something informative.