Friday, March 22, 2013

Geo 365: March 22, Day 81: Debris Apron and Ponderosas

Turning away from the Hole-in-the Ground crater, and looking off to approximately the northwest, the debris apron from the series of phreatic explosions that created the feature is subtle, perhaps, but still clear to me, at least. I can't really tell if the slope down and away from the crater is as clear as it seems in the photo, or if I'm simply imposing my own memories in interpreting what I'm seeing. What I will say is this: you can definitely tell you're heading uphill as you approach the turn-off and spur up to the rim, and once you turn onto that spur, there's a very distinct, though fairly gentle, grade up to the parking area. The road cutting across the bottom of the photo circles the crater, though I've never got up the courage to see if it's navigable for regular passenger vehicles.

As I alluded yesterday, I do find it a bit puzzling that the ponderosa pines do so well here, but simply can't get established in most of the crater. The only difference I can point to is elevation, but it seems odd that only a few hundred feet can lead to such a stark contrast.

Photo unmodified. August 20, 2011. FlashEarth Location.


Hollis said...

Might there be shallower bedrock? Pines like to tap into fractures etc -- for water.

Lockwood said...

That may be a possibility- some one of the layers lost in the crater itself may act as a bit of a reservoir. I posted a cross section on Wednesday ( )- not terribly good resolution, but you might want to take a look.

Related, the so-called "Lost Forest" is fairly close to this spot- you may find that wiki page of interest, and it supports your position. "The post-Pleistocene lake environment formed the ash sediments from Mount Mazama into porous ground soil. The soils are underlain by hard calcium carbonate caliche layer several inches thick. This subsurface layer is impervious to water drainage and is seldom penetrated by roots. As a result, ground water is held near the surface." (From the "Environment" section of this article: )

Phill Vanderschaegen said...

Looks like the area just east of Mono Craters. Damn near got stuck in the soft stuff once.

Lockwood said...

The gravel road into this area can be pretty rough; they only grade it every few years or so. But even wet, it's drivable (if messy). Just have to take it slow. No worries about getting stuck, here, but some areas of eastern-central Oregon I definitely avoid when there's been precip.