1 January 2016

Friday fold: Folded Mountains Ale

My friend Eric Pyle drew my attention to this ale earlier in the week –


I reckon that will do for this week’s Friday fold. Cheers! And Happy New Year!

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31 December 2015

2015 Yard List


It’s that time of the year – a time to state my “yard list” tally for the previous year.

I have been posting this list every year since I moved to the Fort Valley:

In 2015, we had 65 species of birds spotted and definitively identified in our yard. In order of first appearance, they were:

  1. Carolina wren
  2. Dark-eyed junco
  3. American goldfinch
  4. White-breasted nuthatch
  5. Downy woodpecker
  6. Tufted titmouse
  7. Chickadee
  8. Mourning dove
  9. Red-bellied woodpecker
  10. Pileated woodpecker
  11. Cardinal
  12. Hairy woodpecker
  13. Red-shouldered hawk
  14. Brown creeper
  15. Eastern bluebird
  16. Sharp-shinned hawk
  17. Turkey vulture
  18. Purple finch
  19. Red-tailed hawk
  20. Blue jay
  21. Turkey
  22. Raven
  23. Canada goose
  24. Crow
  25. Pine siskin
  26. Hermit thrush
  27. Brown-headed cowbird
  28. Eastern phoebe
  29. Barred owl
  30. Pine warbler
  31. American robin
  32. Whippoorwill
  33. Chipping sparrow
  34. Black vulture
  35. Double-crested cormorant
  36. Broad-winged hawk
  37. Blue-gray gnatcatcher
  38. Ruby-crowned kinglet
  39. Northern flicker
  40. Yellow-rumped warbler
  41. Ruby-throated hummingbird
  42. Ovenbird
  43. Red-eyed vireo
  44. Common nighthawk
  45. White-throated sparrow
  46. Common grackle
  47. Chimney swift
  48. Eastern wood-peewee
  49. Great crested flycatcher
  50. Worm-eating warbler
  51. Brown thrasher
  52. Cedar waxwing
  53. Yellow-billed cuckoo
  54. Great blue heron
  55. Scarlet tanager
  56. Screech owl
  57. Black and white warbler
  58. Bald eagle
  59. Osprey
  60. Winter wren
  61. Black-throated green warbler
  62. European starling
  63. Kestrel
  64. Yellow-bellied sapsucker
  65. Golden-crowned kinglet

I’m pleased each year to have exceeded the previous year’s count. I think it’s an indication of some combination of awareness/ familiarity and simple “time spent outside looking at birds,” both of which are good things. This was an especially good year for raptors, and I think I’m getting better at identifying migrating passerines.

Here are a few more photos:





Here’s hoping 2016 is even more birdy than 2015 was!

Happy new year.

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29 December 2015

Serpentinite mélange on Marshall’s Beach

Another geological pilgrimage I made in San Francisco earlier in the month was to Marshall’s Beach, just south of the Golden Gate Bridge. I had first visited this site 5 years ago with my friend Alan Pitts. It is a great place to see a tectonic mélange of serpentinite.

Looking toward the Golden Gate from the fortification called Battery Crosby, you can see our destination – the greenish slopes along the shore.


See the cluster of rocks directly between this perspective and the bridge? That’s where we are headed next…


Some of the fresh exposures of serpentinite mélange make my heart swoon…


Here is a relatively coherent block of former seafloor, surrounded by a goop of sheared out and wet-metamorphosed rock that probably once looked much the same.


Blocks like these are frequently sheathed in slickensides, such as this one here:


It’s a beautiful place to visit. But if you can’t make it yourself, here’s a GigaPan of the outcrop above to explore:

Link Image by Callan Bentley

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28 December 2015

Corona Heights Fault, San Francisco

On my final day at the AGU Fall meeting, I made a pilgrimage to a place I’d long wanted to visit: Corona Heights, where there is a subvertical exposure of a fault, bedecked with both fault breccia and the most amazing set of slickensides I’ve ever seen. I was able to find it easily thanks to the awesome map that Christie Rowe made for AGU visitors to get a taste of local geology.

From the plunging orientation of these lines, raking across the subplanar fault surface, we can deduce the kinematics (motion) of the fault. In this case, it’s an extraordinary example of an oblique slip fault, cutting cherts of the Franciscan complex.


“Slickensides” is a general term for linear features on a fault surface. The lines may be grooves that result from gouging, in which case we can call them slickenlines, or they may be mineral crystals that grow in small extensional spaces along the fault surface, in which case we might refer to crystal fiber lineations. At Corona Heights, it’s slickenlines, and they are profoundly well developed, well exposed, and well preserved.


They are also coated in many places with a silica gel, making the fault mirror-like in its reflectivity when viewed from certain angles. Here is the perspective looking up the cliff at the same spot as the previous photo, showing the reflectivity of the fault surface:


The exposure is steep (note the rowhouse roof line in the background as a horizontal reference):


Swiveling our perspective to the right, here is an animated GIF to show the shiny surface of the fault:


At one place, the fault surface (and its slickensides) have broken off, revealing a look deeper into the footwall. There, you can see a fold in the chert layers:


Here, the slicks plunge into the ground, neighbored by a zone of fault breccia, upon which the pencil lies:


Close-ups of the breccia:



I brought the GigaPan:


Here are the resulting explorable GigaPan images, the result of about two hours spend on-site. Can you find the scale pencil? Can you find exposures of breccia? Enjoy exploring them for fun details.

Link Image by Callan Bentley

Link Image by Callan Bentley

Link Image by Callan Bentley

This is a world-class site. If you have any interest in faults, it should be your top stop when next in San Francisco.

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27 December 2015

Superintelligence: Paths, Dangers, Strategies, by Nick Bostrom

owl How much thought have you given to the consequences of achieving an non-biological intelligence?

If you’re like me, you’ve thought about the notion in a Hollywoodized sense, but once you get out of the cinema showing the latest Terminator film, you might not dwell on the topic too much further.

I’ve given artificial intelligence (AI) a little more thought than that in the past six months, largely spurred on by fortuitously stumbling across these two excellent blog posts by Tim Urban at the website Wait But Why:

The AI Revolution: The Road to Superintelligence, and

The AI Revolution: Our Immortality or Extinction

Those are a great place to start – to bring you up to speed on some of the issues, before you consider investing in Nick Bostrom’s book Superintelligence, the subject of this brief review. Everyone should read them to get a sense of the scope (almost unimaginable, with many manifestations that could represent an existential threat to our species, and all life on Earth, and all life in the universe) and temporal immediacy of the rise of machine intelligence. Go do it.

A month or so ago, the New Yorker published a piece about Bostrom and his ideas called “The Doomsday Invention.” That is also worth reading. It’s more of a profile of Bostrom, who has had an interesting history and has interesting work habits. But ultimately, it’s a good precis of some of his ideas, too.

Prompted by this new article, I decided to jump in and read the book everyone referred to as the source of many of these ideas. Superintelligence is a fairly dense book in many parts, but the rigor of Bostrom’s thinking is palpable. He ventures down many many intellectual paths, considering implications and strategies that might be employed to avoid the worst outcomes. He considers the economic effects of superintelligence, and what a stable AI would mean for our socio-political system. He considers the ethics of how we treat digital minds – once a machine has attained human-level intelligence, is it ethical to switch it off? What would be the legal standing of such an entity? At what level of intellectual achievement would a digital mind gain legal standing? As a result of the “expanding circle” of empathy coupled with familiarity with digital minds, will we someday look back at the slaughter of “bad guy” characters in video games as a moral transgression equivalent to the extirpation of bison on the American steppe? It takes an original mind to pose such questions, and Bostrom’s not afraid to think the unthought.

Most of the book, though, dwells on the bigger issue of the dangers of machine intelligence, and most of my interest in the book stems from that same source. Bostrom makes a strong case that if a machine superintelligence turns against us, it won’t come with a “Skynet” sort of plot line, but will instead be because of something awfully inane, such as we program the computer to maximize paper clip production, and it sees our bodies as either a source of atoms or a source of energy for making paper clips. Thoughtless design of the paper clip-manufacturing AI results over geological time (spoiler alert) in the entire cosmos being converted to paper clips. No malice, no vengeance, simply a computer program doing what it’s been assigned to do, in the most efficient, comprehensive way possible.

The key things I gleaned from Bostrom’s exhaustive treatment of the subject are  that (1) superintelligent AI could happen really quickly, (2) the ‘intelligence’ will mostly likely not be like human intelligence, but will be of an utterly alien flavor that will not be emotionally/intuitively comprehensible to us as humans, (3) there are so, so, so many unknowns that we should really try and nail some of this stuff down now, before it’s too late. On this last note, I was astonished how many of the intellectual arguments that Bostrom articulates end in a big question mark. This book appears to me to be rigorous and intensely well-thought-out, but it does not in any way present “the answers” to its readers. The known and unknown unknowns are many – and having them so precisely enumerated leaves me feeling very unsettled. There are a lot of different ways that this could go really, really wrong, and it’s not clear how many ways there are for it to go right.

If Bostrom is right, and I see no reason to think anything else, the rise of machine intelligence is possibly the most important thing to happen on this planet since the first replicating cells, or the rise of multicellularity, or the ripening of human intelligence. Many groups are working on AI, in many settings (commerical, university, perhaps government, perhaps hackers) and who knows which of them will get there first. If one of those human-level AIs gains the ability to “bootstrap” its own intelligence, it could go from human-level AI to superintelligent AI in some relatively short span of time, perhaps hours. The lead time to prepare for superintelligence may be horrifically short. If this goes wrong, it could do so in a way that is not only spectacularly important for humanity’s existence, but all life on Earth, and indeed all matter in the entire universe! We are rushing toward the development of artificial superintelligence, and probably we will get there sometime in the next century, and when we do, it may alter the course of the universe forever. Pretty high stakes.

I hope that the book Superintelligence prompts more attention to the potential pitfalls of AI, both in the specialist community that works on AI issues, but also in society in general.

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24 December 2015

Cryptonomicon, by Neal Stephenson

cryBecause I was impressed with Seveneves, I decided to make my next read another novel by Neal Stephenson.  There are several highly-praised options to choose from, but the one that came to hand first in the library was 1999’s Cryptonomicon. It’s a monster of a tome, clocking in at just over 900 pages, which is a good reason you haven’t seen any book reviews from me in this space over the past month. It took a long time to read all that. But the reading was very enjoyable – Stephenson is a virtuoso writer, and to run one’s eyeballs over his sentences is a treat for the mind. He offers a blend of technical detail, character portraiture, reflections on modern life, tasty vocabulary, and awesome analogies that make the reading a totally fun time, regardless of topic. In this case, the topics are: code making and code breaking, computers, World War II, gold, digital currency, and southeast Asia. In contrast to Seveneves, the cast of main characters are all male, set in two eras: during World War II, we follow the stories of an American soldier, a Japanese soldier, an American code-breaker (and confidante of Alan Turing), and a mysterious priest. During the “modern day” (late ’90s, nascent tech boom), there is one main protagonist, a descendant of one of the WWII characters, and he interacts with the descendants of several of the other characters as well as with some old-timers who span the two periods. Ultimately, it all comes down to a tremendous cache of Japanese war gold, but when they get there, it feels like a moderate let-down. I’ve been told that this is frequently the case with Stephenson novels – that they have this ‘feel’ of building towards something powerful and major, but that the climactic payoff is frequently the weakest part of the book. That’s how I felt with Cryptonomicon – there was enough of a momentum to keep me flipping 900 pages, but when I got to the end, I wondered if I had really gotten anywhere.

Additional critiques: It’s tough to read the 1999-era computer stuff with the hindsight available from late 2015, so that part of the book doesn’t hold up so well in a way that feels fresh or compelling. With one exception that I noticed, Japan is referred to as Nippon throughout, with derivative adjectives like Nipponese standard vocabulary. This isn’t wrong or anything, but it did feel strange. There are several items that are raised and then never really explored or resolved – key numbers, secret societies, motivations of certain characters. It feels kind of like a wordy season of LOST in that regard…

That said, it’s got to be written really well if its going to hold one’s attention over close to a kilopage, and it was. It’s hard not to be impressed by Stephenson’s lexical ability, even if I didn’t close the book with a feeling of satisfaction achieved.

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23 December 2015

Four new GIGAmacro images of sedimentary rocks

It’s been a week and a half since Mountain Beltway has seen any publishing action, given the overlapping timesucks of the AGU Fall Meeting and the end of the semester. But now I’m back in the Appalachian mountain belt, and my grades are all in, and I have time to think about indulgences like blogging again. Let me make up for it now with a suite of four new macro Gigapan images for you to explore:

Trace fossils in Millboro Formation siltstone (Devonian):
Link Image by Callan Bentley

Cross-beds in Massanutten sandstone (Silurian):
Link Image by Robin Rohrback

A trilobite fossil from the Devonian of Morocco:
Link Image by Callan Bentley

And a slab of Devonian-aged Spechty Kopf diamictite:
Link Image by Robin Rohrback

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11 December 2015

Friday fold: Nice gneiss from Salt Lake, Utah

Another guest Friday fold… this one from my colleague Tiffany Rivera of Westminster College in Salt Lake City, Utah, the one who brought you yesterday’s thrombolite pictures

Tiffany writes that these shots come from

a man-made boulder field / berm along the lake. The boulders were these beautifully folded gneisses. Antelope Island exposes some of the oldest rocks in the Salt Lake valley, but I don’t know the geology out there very well. I’d assume that the boulders were harvested on the island.


Here’s the good stuff:



Lovely! Thanks for sharing, Tiffany.

Happy Friday, everyone. I hope to see a lot of you next week at the fall meeting!

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9 December 2015

Thrombolites of the Great Salt Lake, Utah

I saw mention of thrombolites exposed along the shore of Antelope Island in the Great Salt Lake the other day in my Facebook feed; because the description cited a professor at Westminster College in Salt Lake City, I prompted my friend and colleague Tiffany Rivera, also a geology professor at Westminster, to go check it out and get me some bloggable photos. As it turned out, she already had – and was there on the day the Facebook post photos were taken. But she was willing to share some images anyhow. These shots are hers…





Thanks for sharing, Tiffany!

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8 December 2015

Considering the Spechty Kopf diamictite

I have known for a long time about a diamictite in the latest Devonian part of the Appalachian stratigraphic sequence, since it is exposed in the lowermost part of the section (western end of the outcrop) at Sideling Hill, Maryland. When I led field trips there, I talked students through the multiple possible origins for diamictites (sedimentary rocks that are poorly sorted, with significantly “outsized” clasts “floating” in a finer-grained matrix): they could be glacial in origin, or they could be mass wasting deposits, like those that result from submarine debris flows.

When they opened up a new section of the superhighway-to-nowhere, Corridor H, in West Virginia, a couple years ago, one of the road cuts revealed another exposure of this curious unit. For me, this triggered a renewed interest in the Spechty Kopf diamictite. I now had a name to put to it*, and I was eager to read that David Brezinski of the Maryland Geological Survey interpreted the Spechty Kopf as glacial in origin. He had some good evidence in the paper: (1) dropstones that clearly truncate sedimentary laminations, and (2) faceted and striated clasts. Until just recently, I hadn’t seen those for myself… but I was out at the new outcrop for a day of field work during the week of Thanksgiving, and was able to spend an hour looking at the unit.I found several things that convinced me that glaciation had a role to play in the deposition of the diamictite.

Here’s a typical look at its poorly sorted nature, and the angular / faceted shape of some of its large clasts:


There are two distinct sedimentary textures to this unit: a laminated subunit with outsized dropstones, and a massive unit with no internal layering. The image you just looked at is from the massive subunit. Everything else in this post is from the more interesting laminated subunit:

A big, oblong granitic clast (between my index finger and thumb), cutting across laminations:


Another, rusty orange on its exterior:


Some of the best views of the relationship between the outsized clasts and the laminations were not found in outcrop, but in float piled up at the base of the outcrop. Here’s my favorite example:


Zooming in on the most prominent two granitic clasts:


…And with the trace of bedding highlighted, showing the truncating relationship these pebbles have with their matrix. I am confident in identifying these as dropstones, based on the way they appear to squish down into the laminations:


That’s key, for me. Massive diamictites may be due to glacial deposits or to debris flows, but dropstones are a surer indication of glaciation. However, it should be noted that these strata are Devonian, and that plants had evolved by the Devonian. Therefore, at the time these strata were deposited, there existed more than one mechanism to raft big clasts of rock out over fine-grained deposits of mud: it could be icebergs, but it could also be sedimentary particles caught in plant roots. There are carbon films of plant fossils in this unit, and I’ve also seen fern fronds preserved as impressions.

The real prize find of the day was a single clast (a pebble) that showed both a faceted shape and striations on the facets. Here it is:




Plants can’t be held responsible for that! These scratches are strongly suggestive of glaciation.

I think the Spechy Kopf diamictite may be the most interesting unit in the Paleozoic sequence in the Appalachian basin. More on it later…


* The name comes from the type locality, near a mountain in Pennsylvania with a name that’s German for “Woodpecker head.”

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