Valles Caldera Geology Tour (Part 5 of 6): Lakes and Volcanoes

Lakes and Volcanoes - At this overlook of San Diego Canyon, from the SW border of the Valles Caldera, we will discuss the history of lakes and volcanoes inside the caldera. For the past half a million years, San Diego Canyon is the only outlet for meteoric water (rain and snow) from inside the caldera. Of particular interest is the last ring-fracture volcano, which produced the El Cajete crater, which erupted explosively to produce tephra and pyroclastic flow deposits. Later, a thick, pasty, rhyolite lava oozed from the crater about 40,000 years ago, creating the Banco Bonito lava flow. Much of this flow is obsidian, a volcanic glass, and exhibits giant topographic wrinkles termed ogives.
Javier Sernas - jsproductions....

[@angelathrall3896]

Very thorough series on this topic, very well done! Great information! Thank you!

[@buzzyhardwood2949]

Excellent explanation and use of visuals, especially the Google Air shot of the caldera that you color-coded for the various pyroclastic flows. Thank you so much for making this caldera “real”. Amazing geology.

[@flyfishing1776]

Thank you. . I've hiked that area and you have answered many of my questions 👍

[@TheSongoftheriver]

As someone born and raised in Los Alamos, I really love the detailed explanations here. I did have a question: is there an estimate of how high the volcanoes were prior to the caldera collapse? I had a science teacher there tell me that some thought the peak might have been higher than present-day Everest, but he couldn't really cite anyone's research into that.

[@TheSongoftheriver]

Never mind...made it to the "myths" section of the last video, where this is dispelled. Thanks again!

[@cjm081]

Lol. "Not weapons grade material.".... Very appropriate given the proximity to the Los Alamos National Lab.

[@brianbechtol7329]

Is it known why the ring fracture volcanoes traveled in a counter-clockwise direction chronologically?

[@autotek7930]

Righty tighty, lefty loosey

[@jeffcotton2120]

Yeah i’m Going with that the second eruption that blew out the lake, happened generally around the same time. And was more of a lower pressure steady acid flow, after the erupting pressure broke down the SW wall. Then carved a canyon from the SW wall down to the Valley stemming from it. The blobs in the middle look to be the main thrust points of break through pressure. Then the semi circle of smaller pop up Volcanos, look to be lower pressured pop ups that pointed combined pressure points with the main center break throughs, & found a way out threw the breaking SW wall. The directional flow is materialized & solidified with the larger center blobs that popped up.

[@tommunyon2874]

Ironic the obsidian is "not weapons grade", as 'ogive' is also a feature of military shells.