geeking out on geology

[111]

does anyone know if the rock at Columns in Eugene is Columbia River Basalt?

[gruntpltleader]

Let me know exactly where it is, but I don't think the the CRFB's came that far south. I think it is part of the Little Butte Volcanics or some of the other older cascade volcanics. College geology is kind of fuzzy yet, but look in Geology of Oregon, Orr and Orr. They would know if any one.

Edited March 7, 2007 by gruntpltleader

[Alasdair]

no its not

[Ptown_Climber1]

My understanding was that most of Oregon from around that area north was all Columbia River Basalt if you dig deep enough....Thanks to Missoula Floods it's mostly buried under rich topsoil scoured out of eastern Washington and Idaho. Ancient flows of the Columbia emptied out around Newport, so it could very well be.

[MarkMcJizzy]

My understanding was that most of Oregon from around that area north was all Columbia River Basalt if you dig deep enough....Thanks to Missoula Floods it's mostly buried under rich topsoil scoured out of eastern Washington and Idaho. Ancient flows of the Columbia emptied out around Newport, so it could very well be.

 

The definitive work on Columbia River Basalt distribution ( Bentley, Riedel, Swanson, and others (1987)), shows the CRB’s flowing out of the Columbia Basin, squeezed by the proto Cascades in the Columbia Gorge. The flows then entered the embayment of the Willamette, and extended to just south of Salem. In the Astoria area they were constrained by the Coast Range on the south. Breaching this, the flows traveled south along the coast, to at least Florence (if I remember correctly).

 

I spent four fun filled days following the Columbia River Basalts to the ocean with Dr. Robert Bentley in 1984.

[ivan]

voodoo witches! heretics!

 

[111]

thanks for the seriously indepth info folks!