Geo 365: May 26, Day 146: Newberry's Central Rift

(Right click, and choose 'open link in new tab' for full-size gloriosity) The view north from Paulina Peak, over the so-called "central rift." I say "so-called" because I think of a rift as a linear pull-apart zone. This feature is clearly linear, but it's not clear to me that it necessarily anything more than a fault zone- an area of weakness that gives magma an easier path to the surface.

On the far side, the Interlake Obsidian Flow erupted near the edge of the caldera, flowed down slope, and split to reach both Paulina and East lakes- though the finger to East Lake is hidden behind the Central Cinder cone from this vantage point. Since that flow is clearly conforming to the topography of the Central Cinder Cone, the latter must be older. There's a smaller, unnamed, as far as I know, cinder cone between the road and the Central Cone. It looks as if a late stage lava flow may have breached that cone to the west. Finally, the toe of the Big Obsidian Flow occupies the lower right corner of the photo.

All four of these features are pretty clearly controlled by a single structure, the central rift. I've read that this same rift is responsible for the locations of quite a number of cinder cones, out to, and including, Lava Butte! It's possible to kinda sorta trace out this lineation in FlashEarth, but there are just so many cinder cones that I personally wouldn't feel comfortable about making that claim without a whole lot of supporting evidence. It seems like you could just about drop a line anywhere and find a bunch of cones aligned on it. But the example above is pretty cut-and-dry, to my eyes, at least.

Panorama stitched in HugIn, otherwise unmodified. August 21, 2011. FlashEarth location.