Category: • Personal Notes •

Notes on the Geology of Baja

Wednesday, 7 December 2022

Summary

  • 200 Ma, on: Subduction of the Farallon plate resulted in arc volcanism that produced a range of mountains along the west coast of North America. (These will eventually erode, and their batholiths will be exhumed and form today’s mountains and the eroded sediment will accumulate in basins forming soil and lithifying into sedimentary rock.)
  • 20 Ma. As the Farallon plate completed its subduction, it broke into microplates, and
    (1) SAFS. the East Pacific Rise subducted initating the transformation of a convergent margin into a transform margin and the San Andreas Fault system, and
    (2) Cabo volcanoes. continued subduction of the microplates produced volcanism that can be seen around Cabl
  • ~17 Ma. Complex tectonics, due to the SAF system, that I don’t really understand, generated the basin and range system farther north, and this in turn is thought to have channelized the stress that eventually opened the gulf of California.
  • ~15 – 6 Ma. Tectonics lead to capture of Baja by Pacific plate, transitional shearing in the proto-Gulf of California, and at 6 Ma the beginning of the ‘unzipping’ of Baja.
  • ~3.5 Ma. Development of spreading centers in the Gulf of California, and extrusion of mostly basaltic oceanic crust.
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What is this Rock, 3: Course Notes

What is this Rock, 3

I just returned from a weekend up on the North Shore. K and I went up and stayed at Cove Point Lodge, while I took a 3-day course on North Shore Geology, focusing on the Beaver Bay area. The course was taught by Jim Miller, a retired Minnesota Geological Survey person, and an emeritus professor from UMD: he was a great person to teach the course, both because he was a good and enthusiastic instructor, and because he has spent his career focused on the northern Minnesota in general, and the North Shore in particular. Many of the geological maps of the north shore include his name as cartographer.

This is a laundry list of what I learned — however, there are problems with the images which I have yet to fix.

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Iceland 2020, Day 1: Reykjanes Plans

Tuesday, 26 July 2022

While I had intended to report on the trip in this blog, it turned out, since I was writing on my phone, to be easier to do a series of daily posts to Facebook. So this is the last bit on Iceland here, at least for the moment. I plan to edit and expand the FB posts, and will eventually post them here, or in a another of my blogs.

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Geology of the Peninsula*

*Much of this is adapted from https://en.wikipedia.org/wiki/Geology_of_Reykjanes_Peninsula

The Reykjanes Peninsula is the continuation of the submarine Reykjanes Ridge, a segement of the Mid-Atlantic ridge. It reaches from the Esja volcano in the north to hengill in the east and Reykhanesta in the west. It originated 6-7 Ma in a rift-jump, after the Snæfellsnes-Skagi rift had drifted to the west out of range of the presumed location of the mantle plume.

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Iceland 2022, Day 0: Recovery Day in Reykjavik

Monday, 25 July 2022

A good night’s sleep

https://norse-mythology.org/symbols/svefnthorn/Norse Sleep Rune

As I’ve aged I find that I fare less well on less sleep; or perhaps, I never fared well on less sleep, but when young was too inexperienced to notice my own deficits. Regardless, I scheduled my trip to have a ‘recovery day,’ so that I wouldn’t be dragging on the first day of the tour. Additional benefits are decreased stress — I was unconcerned the cascading delays of the day before would cause any disruption in my schedule – and a chance to wander about Reykjavik.

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Iceland 2022, Travel Day: The Yellow Duffle

Saturday-Sunday, 23-24 July 2022

I have been looking forward to the Iceland trip for quite a long time. It had initially been scheduled for the Summer of 2021, but Covid concerns derailed that. The trip is under the auspices of ILSG –The Institute of Lake Superior Geology – which is a regional association of geologists, both professional and academic. I became acquainted with the group via the Geological Society of Minnesota, and went on an ILSG field trip to the big island of Hawai’i in the winter of 2020, just prior to the advent of Covid. It was a great trip, 11 days with about a dozen folks, and toured the five extant volcanoes of the island, including a helicopter trip to the suburb once known as”Royal Gardens,” now better known as a lava field of black basalt. It was a great trip, and although I am introverted, I very much enjoyed the trip and the people. That the people who led the Hawaii trip were also leading the longer and rougher Iceland trip, was a significant inducement.

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Things I learned from the 2021 Loft Essay course

16 August 2021

Things to pay attention to:

  • Telling details: One telling detail is preferable to many details
  • Embodiment. Emotions and actions work best when embodied: gaze, gesture, posture, proprioception, proxemics
  • Scenes. Scenes should vary in length, and be interleaved with summaries. This gives rhythm and weighting. Think of a scene as a spotlight. 
  • Language: avoid ‘to be’s. Avoid “is” “are” “have” etc. and limit use of adjectives. 
    “To be” is the weakest verb. Not “He is tall” but “He smacked his head on the door frame”
  • Language: avoid distancing: Avoid habitually using filtering/distancing language such as “I noticed,” “I heard,” “I saw,”  
    (That said, sometimes you may want to use it to distance yourself, as when you are uncomfortable and don’t want to be in it.) 
  • Language: avoid adverbs. Use actions and embodiment rather than adverbs:
    “Yeah,” she said, stroking his bare arm, “that’s what I heard.” vs. “Yeah,” she said gently, “that’s what I heard.”
  • Support reader inference. There is something about readers being able to figure something out on their own that is very rewarding.
  • Revising Tricks: Print it out in a different font. Read it out loud and notice where you stumble, speed up, lag, etc. Replace “to be’s”

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