Urban Natural History: Two Geological Layers at Clark Creek Park

Tired of transit? Yeah. Here's something more quiet.

The other day some of the Parks sites shared a photo from Clark Creek Park. There's a tiny little falls and pool there that shows a distinct seam between two geological layers.

Clark Creek at Clark Creek Park - Rigo Macio
via City of Salem Parks Volunteers

Close up showing reddish Jory soil and chunky, basalty rock

One of them is the reddish Jory soil characteristic of many hills around here, many farther out from the city with vineyards, and the other is this basalty-looking chunky dark colored rock. It looks like a lava flow or something.

Does anyone know anything about this tidbit of local geology? Is that chunky rock the characteristic bedrock around here? Or is this an intrusion over some other more characteristic layer?

The New Minto Park Master Plan has a map of soils (detail)

Are there any other interesting geological features exposed by road cuts or creeks or escarpments you have noticed while walking and biking around town? Another I've noticed sometimes is that as you ascend hills, you can occasionally see a procession from a greyer soil lower down to the reddish Jory soil up higher on the hill. (I don't know what this greyer soil type is called.)

Ever so slightly related, the New York Review of Books has an amazing set of articles (and one interview) up right now. One is on Alexander von Humboldt, who definitely doesn't get enough attention these days, and may be a surprising resource as we think about the challenges of climate change.

More plants, animals, minerals, and places are named after Alexander von Humboldt than anyone else. http://t.co/qJG7OS9YLX

— NY Review of Books (@nybooks) October 13, 2015

From the piece:

Humboldt’s most consequential findings, however, derived from his conception of the world as a single unified organism. “Everything,” he said, “is interaction and reciprocal.” It seems commonplace today to speak of “the web of life,” but the concept was Humboldt’s invention. Into the seventeenth and eighteenth centuries, thinkers like René Descartes, Francis Bacon, and Carl Linnaeus were still echoing Aristotle’s view that “nature has made all things specifically for the sake of man.”

Particularly heterodox was the implication that the decline of one species might have cascading effects on others. The possibility that animal life might not be inexhaustible had been proposed by the German anatomist J.F. Blumenbach (who taught Humboldt at the University of Göttingen), but was not widely accepted. “Such is the œconomy of nature, that no instance can be produced of her having permitted any one race of her animals to become extinct,” declared Thomas Jefferson in 1784, an opinion shared by most naturalists. Convinced to the end of his life that mastodons still existed in North America, most likely in the “unexplored and undisturbed” regions of the continent, Jefferson urged Lewis and Clark to look for them during their expedition.