Friday, October 19, 2012

Corvallis Geology Map

I have been informed by various geobloggers, notably and most delectably by Silver Fox, that today is geologic map day. So here's the geology of my little burg:
Mappable units include, from youngest to oldest,
  • Qtl- Quaternary terrace, low (Willamette gravels and other sediments)
  • Qtm- Quaternary terrace, mid-level
  • Qth- Quaternary terrace, high
  • Ti- Tertiary intrusive (Mafic, mostly diabasic in texture)
  • Ts- Spencer Formation (near-shore marine deposits)
  • Tf- Now classified as Tyee, turbidite deposits called Flournoy Formation at the time.
  • Tsr- Siletz River Volcanics
Other features:
  • The Corvallis Fault has uplifted older Tsr with respect to younger sedimentary units along the slash from upper right to lower middle
  • Pediments are identified by diagonal cross-hatching
  • Areas of particularly high slope (and thus high mass movement risk) are identified with dark gray shading
Chip Ross Park, where I went with Dana Last week, is near the top of the image, to the right of the "Tsr" label, and with the little "apostrophe" of shading to mark a steep slope. Avery Park, where we went next, is at the bottom on the right. You can see the full map and legend in zoomable flash format here. Scroll down a bit, and above the line "Select an image to view / download," click on the first image.

1 comment:

Silver Fox said...

Nice idea to post a local map for map day. :)