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Lava field at McKenzie Pass


Heading north from McKenzie Pass, the Pacific Crest Trail trail clings to a couple of "forested islands" then works its way across a rugged expanse of fresh basalt (in geologic time). Belknap Crater, a shield volcano and source of the lava field, is the red cone in the background.

Most people focus on how barren the basalt landscape appears. Phytocurious people, however, want to know which plants are pioneering the colonization of this habitat. Aside from the lichens (which are not plants), there is an occasional conifer and here and there a Vaccinium. Seeds of the conifers probably blew in and the huckleberry was deposited by a bird.

Lava notch McKenzie Pass.jpg

In one of these slots, I found a colony of mountain bentgrass (Agrostis variabilis), right. Other pockets of soil were home to bottlebrush squirreltail (Elymus elymoides), ticklegrass (Agrostis scabra) and a needlegrass (Achnatherum sp.) because I did not venture far enough off the trail to collect it (below).


There were a number of grasses that had also established from wind-blown seeds, finding sheltered places in the rough basalt where soil collected. As the surface solidified, the hot basalt flowing underneath created an uneven topography including pressure ridges, tubes and linear slots.

Agrostis variabilis McKenzie Pass 2.jpg
Belknap Craters-4.jpg
Belknap Craters-2.jpg

I'm looking forward to exploring north toward Mt. Washington along this trail, but it will have to wait until next year. Winter is closing in on the crest of the Cascades.

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