Uploaded August 2021 | Updated September 2026, 2 weeks ago
Port Townsend is a beautiful historic port city in northern Washington, and like most of the region its geologic history is dominated by giant glaciers. Learn all about them here, on BetterGeology!
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A quick note: The block I identify as a glacial dropstone is actually something called a rip-up-clast. The meltwater flowing away from the melting glacier tore chunks off an outcrop of mudstone and dropped them nearby, rather than the blocks being transported by glacial ice. There are dropstones in the area, but the one I highlight is not one of those. My apologies for the error!
Port Townsend is a beautiful historic port city in northern Washington, and like most of the region its geologic history is dominated by giant glaciers. Learn all about them here, on BetterGeology!
––––––––––––––––––––––
If you like what I do, please consider supporting me on Ko-Fi!
ko-fi.com/bettergeology
––––––––––––––––––––––
A quick note: The block I identify as a glacial dropstone is actually something called a rip-up-clast. The meltwater flowing away from the melting glacier tore chunks off an outcrop of mudstone and dropped them nearby, rather than the blocks being transported by glacial ice. There are dropstones in the area, but the one I highlight is not one of those. My apologies for the error!
![Geology of the Alvord Desert | Oregon Geology - 4K [CC]](https://i.ytimg.com/vi/xYUxSZgL1p8/mqdefault.jpg "Geology of the Alvord Desert | Oregon Geology - 4K [CC]
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The Alvord Desert is Oregons largest dry lake bed, and it is at the center of a fascinating geologic story. It sits in the shadow of Steens Mountain, one of Oregons highest mountains which towers more than 5,000 feet above the lake bed and creates the rain shadow needed to maintain Alvords desert-like conditions. Steens Mountain was uplifted over the past 10 million years along the Steens Fault, and more than 3,000 meters of total offset has occurred in that time. Alvord Desert filled the graben that that fault system created. Above Alvord Desert in Pike Creek, older volcanic rocks can be seen which reflect an interesting volcanic environment which produced highly-evolved rhyolite lava shortly before the massive outpouring of the Steens Basalts (part of the Columbia River Basalt Group) blanketed Oregon. These older volcanic rocks of the Pike Creek Volcanics also contain some of Oregons few uranium mines. Uranium was concentrated in old fault zones, and the presence of heavy metals shows that the Steens Fault extends very deep into the Earth. This deep structure is also what allows the numerous hot springs (Alvord Hot Springs, Mickey Hot Springs, and Borax Lake) to reach the surface.
This video was filmed by and with camera gear provided by Riley Hooper, who can be found over at Wogos Media.
The data for the Columbia River Basalt dikes is from Morriss et al, 2020 paper The Chief Joseph dike swarm of the Columbia River flood basalts, and the legacy data set of William H. Taubeneck published in Geosphere. https://doi.org/10.1130/GES02173.1")
