Recent Twitter Geophotos

Most Mondays, at least when I remember, and from time to time on other days, I post a geology photo on Twitter. Now that I have time and a cooperative computer for blogging, I figured I'd repost some of those recent photos here- not everyone is interested in playing the Twitter game. To be clear, I tend toward things I've recently done and seen, but my Twitter geophotos have no real rhyme or reason; they're just images that appeal to me at the time. (They'll get bigger if you click on them.)

"Looking forward to Silver Falls tomorrow. North Falls plunge is 136 feet." (North Falls, Silver Falls State Park, Oregon)

"Couple of Monday Geophotos: ledge of Grand Ronde Columbia River Basalt over seds, North Falls, Silver Falls SP, OR." (Note people for scale; this alcove is huge!)

"#2, looking up from ~ where people are in 1st photo: tree trunk casts; trees growing in seds swamped by CRB flow." (North Falls, Silver Falls State Park, Oregon)

"Monday geophoto: Fossiliferous sandstone in CCC building, Silver Falls St Park, Oregon. Mostly pelecypods."

"Monday Geophoto: Petrified wood at Sweet Home Community Museum." (Flash Earth link, crosshairs on shadow of sheltering awning. Sun/shadow geometry very nearly the same in linked image as in the above.)

"Monday Geophoto: Petrified wood at Sweet Home Community Museum- cross section of top of log."

"Monday Geophoto: cross section of top of log, closeup. Lens cap is 52 mm."

"Monday Geophoto: Volcanic neck, ~7.9 mile past Green Peter Dam, Quartzville Area (Auto levels for contrast)."

And here's today's:

 "Monday Geophoto: pyrite on a jointing surface, currently unused quarry, Quartzville area, Oregon."

Sunday Funnies: Cautiously Re-Testing the Waters Edition

It's been quite some time, but this electronical difference engine is (for browsing purposes anyway) much faster than my old one, which with respect to the web, was more of an abacus than a computer. This one has a glitchy screen, and I don't think it will be as good with media, but I've been able to get through quite a bit more than usual today. I've gotten out of the habit of setting funnies aside for Sundays, so this actually is a compilation of the things I've marked since early May. We'll see if I can fire that habit back up again.

Darius Whiteplume's Tumblr

Pundit Kitchen

Surviving the World

Bits and Pieces

Savage Chickens

"Captain Canada: so Canadian he pisses maple syrup" Sofa Pizza

 Sober in a Nightclub

Darius Whiteplume's Tumblr

 

Very Demotivational

Sober in a Nightclub

Wil Wheaton's Tumblr

So Much Pun

Married to the Sea

RoflRazzi

Bizarro Blog

Very Demotivational

Bizarro Blog

Sober in a Nightclub

"Looks like Boo grew up." RoflRazzi

Comixed

I Can Haz Cheezeburger

I Has a Hotdog

Engrish Funny

I Can Haz Cheezeburger

Bizarro Blog

Julia Segal Time

Cyanide and Happiness

If only she was running... Epic4Chan

...and on a good day, it took half an hour to download a 100K jpeg. Comixed

Fake Science

Blackadder

Very Demotivational

Bits and Pieces

Picture is Unrelated

Wil Wheaton's Tumblr

Bits and Pieces

I can Haz Cheezeburger

...and that's why I love teaching, and teaching geology especially (click over to read the hovertext). xkcd

Willamette Valley Geology Online Resources

Last Saturday I presented for a workshop on Willamette Valley Geology for the Oregon Master Naturalist Program (henceforth OMN), an outreach program by Oregon State University. I'm now switched over to my new (to me) rebuilt computer, and while I'm not very accustomed to it yet, browsing and reading is definitely going faster than on my old machine, and it looks like I'll have more time to blog.

One of the components I was requested to submit was a list of online resources, and there's no doubt in my mind that first among those are posts by our wealth of PNW geobloggers, so that makes up the bulk of this list. Note this is not organized by topic, but primarily by blog and the order in which I found them.

In other notes, I'm initiating a label for OMN, to indicate topics that may be of interest to that group- I'll be primarily focused on earth sciences, but will likely include broader science topics dealing with Oregon's fabulous natural history.

Uncovered Earth (Michael Klaas, Portland, Oregon) http://uncoveredearth.com/

• Silver Creek Falls http://uncoveredearth.com/2012/03/06/take-a-hike-silver-falls-state-park/
• Fossils in CCC building at Silver Creek Falls http://uncoveredearth.com/2011/09/27/where-the-mundane-is-anything-but/
• Geo History of Sullivan's Gulch & Alameda Ridge, Portland http://uncoveredearth.com/2011/10/06/a-geological-history-of-sullivans-gulch/
• Picturing Columbia River Basalt Eruptions http://uncoveredearth.com/2011/10/04/hawaiian-fissure-eruptions-then-now/
• From this post http://uncoveredearth.com/2011/09/26/geek-art-lidar-nice-enough-to-frame/ , a LIDAR image of Willamette channel meandering near Corvallis (Older channels are darker blue, current channel darkest) http://www.oregongeology.org/pubs/ll/p-posters.htm#Willamette
• Run-down of PNW Geobloggers http://uncoveredearth.com/2011/09/05/geoblogging-the-northwest/

En Tquila Es Verdad (Dana Hunter, Seattle area) http://freethoughtblogs.com/entequilaesverdad/

• Learning from Lockwood (a very flattering post that made me blush) http://freethoughtblogs.com/entequilaesverdad/2012/07/23/learning-from-lockwood/
• Fun photo of Dana and me at Erratic Rock Wayside http://freethoughtblogs.com/entequilaesverdad/2012/07/10/im-back-feeling-a-bit-erratic/
• Our visit to Silver Falls in March http://freethoughtblogs.com/entequilaesverdad/2012/03/15/the-scenes-we-saw-day-four/

Got The Time (Aaron Barth, recently moved to Eugene, Oregon, just moved from VA) http://iapetancaptain.wordpress.com/

• McKenzie Crossing http://iapetancaptain.wordpress.com/2012/07/12/mckenzie-crossing/
• Skinner's Butte http://iapetancaptain.wordpress.com/2012/07/03/skinners-butte/

Outside The Inerzone (Lockwood DeWitt, Corvallis, Oregon) http://outsidetheinterzone.blogspot.com/

• Gold in Oregon (Not much, but more than most realize.) http://outsidetheinterzone.blogspot.com/2011/04/adoregon.html
• I Slept Through the Big One http://outsidetheinterzone.blogspot.com/2011/01/i-slept-through-big-one.html
• Reverberations of the (Tohoku) quake in the PNW, partway down this post: http://outsidetheinterzone.blogspot.com/2011/03/cobbles-and-gravel.html
• Lotsa Water http://outsidetheinterzone.blogspot.com/2011/01/lotsa-water.html
• Being Careful What I Wish For http://outsidetheinterzone.blogspot.com/2010/12/being-careful-what-i-wish-for.html
• The Geo Biz http://outsidetheinterzone.blogspot.com/2010/10/geo-biz.html
• Show me your sidewalk http://outsidetheinterzone.blogspot.com/2009/06/late-week-geo-meme-show-me-your.html
• The Great Flood http://outsidetheinterzone.blogspot.com/2009/08/great-flood.html

Fluvial (stream) Geomorphology (landforms)

• General overview of "mature" stream landforms http://en.wikipedia.org/wiki/Meandering_river#Associated_landforms
• Nice clear introduction to fluvial geomorphology http://www.scienceclarified.com/landforms/Ocean-Basins-to-Volcanoes/Stream-and-River.html
• Source for Willamette Valley stratgraphic columns and cross section: www.wou.edu/las/physci/.../willamette_geo_field_guide.pdf
• Source for images of meandering stream, oxbow formation: http://www.sci.uidaho.edu/scripter/geog100/lect/11-rivers/11-rivers.htm

New things- posted or found since the above were submitted in August:

• http://www.statesmanjournal.com/article/20120909/OUTDOORS/309090058/1103
• http://blogs.scientificamerican.com/rosetta-stones/2012/08/29/how-would-you-like-to-take-a-hike-across-a-geologic-diagram/ (Dana Hunter's other blog- she started with Sci Am fairly recently)
• http://www.flashearth.com/
• Natrolite http://www.sandatlas.org/2012/03/natrolite/

The Little Robot That Could... Visits Miranda!

Note: This wedge has now been accreted at En Tequila Es Verdad.

This month's Accretionary Wedge (#49) theme is "Out of this World," hosted by Dana Hunter at En Tequila Es Verdad. A similar theme was done four years ago in September of 2008. We've tried to avoid repeating themes that are similar, but this one troubles me not at all, for several reasons. First, it's a little startling to realize just how much has been done and accomplished in four years- that's four extra years of Spirit and Opportunity tooling around in the Martian desert, Curiosity is getting geared up, calibrated, and checked out for its own Martian odyssey, Dawn exploring one asteroid and preparing a voyage to a second, four more years of Cassini exploring the Saturnian neighborhood and moons, and Messenger arriving, doing initial higher orbit observations of Mercury, then descending and starting higher resolution observations in a lower orbit. And THOSE are just the big name probes. Second, the geoblogosphere has seen quite a few new members (including Dana herself), so at this point, I have no problem with repeating or doing similar AW editions to earlier ones. New members, new perspectives. Third, the earth is plenty big, but the solar system is inconceivably huger. There are quite a number of bloggers out there who post almost exclusively on planetary geology (as I grew up calling it) or exogeology (as it seems to be most commonly called now). (Emily Lakdawalla at the Planetary Society Blogs is my favorite.) So it's not as if one AW post on Out of This World Geology was going to put more than a scratch on the countless subjects that could be addressed.

In my post four years ago, my first participation with the AW, I addressed the broad topic of cryogeology, and the idea of how alien it is to us to think of ices as lithic material. While it is quite literally alien from our perspective to think of water and other ices as making up a large or even dominant portion of a large solid body, that is in fact exactly the composition of many bodies in the mid- to outer portion of the Solar System. I mentioned Miranda in that post, and I featured that Uranian moon in my first Moonday post (and the APOD upon which that post was based), but it's my favorite known moon, so forgive me for returning to it yet again.

35 years ago yesterday (September 5, 1977), Voyager 1 was launched into space. Oddly, Voyager 2 had been launched on August 20- if I recall correctly, the reason they were numbered "backwards" was that Voyager 1's path would quickly put it ahead of Voyager 2, even though the latter had a 16-day head start. Voyager 1 was thus able to scout the way at Jupiter and Saturn, and give scientists a better idea of how to target their observations when Voyager 2 passed through those systems later. At launch, Voyager 2 was expected to visit Jupiter and Saturn; extending its planetary mission was contingent on further money being budgeted by Congress, always iffy. However, the budget was extended, and Voyager 2 was pushed deep into Uranus's gravity well, to give a final gravity assist "kick" to also intercept Neptune.

The dive in to Uranus meant that some of the outer moons, which initially were more interesting to planetary scientists, would not be as well observable as had been hoped. And since there was no "scouting trip" by Voyager 1, there would be one chance and one chance only to see what that planetary system had offer. Miranda was not expected to be as interesting as other targets might be, but the path of the probe, and sun/moon illumination aspects would give ample opportunity to study that object. Good thing. Here's a whole-disc image:

At some point in its past, Miranda must have been one of the most geologically active bodies in the solar system. Early speculation was that the moon had been severely impacted, perhaps a number of times, with enough force to disaggregate it, but not enough to cause the pieces to fly apart. That was the story I repeated for roughly 15 years. Then I saw somewhere a new theory that it was impacts and melting, which didn't make as much sense- complete melting would allow segregation of lithics/silicates from ices- and at a density of ~1.2 grams per cubic centimeter, Miranda looks to be a mixture of both. In reading up for this post, I find a much more appealing explanation, which is that Miranda went through a period of orbital resonance with Umbriel, which could have warmed its interior enough to trigger diapirs to develop in the equivalent of its mantle. This would involve solid ice deforming plastically, not melting to liquid. But whatever the explanation, the sense I've always had is that we're seeing enormous depth, compared to the radius of this body, turned over on its side. That fascinates me.

Central in the image above is the feature referred to as the "chevron," and on the right, structures that, as far as is known, are unique to Miranda and Venus, coronae. Looking at the heavily cratered terrain in the upper portion of the image, and down the lower left middle, one can infer you are seeing an ancient, mostly undisturbed surface- much at odds with the dynamism apparent on so much of this small moon. At less than 500 km (300 mi), Miranda would fit easily within the borders of a number of US states.

 

Above, from a NASA image gallery, shows three different terrain types, from left to right, ancient cratered terrain, linearly grooved terrain- an example of a corona- and complex terrain, in which grooves and folds abruptly terminate into each other. Speaking of abrupt, the transition from one terrain type to another is strikingly sudden. Another striking feature pointed out in the Moonday and APOD posts linked in the second paragraph above is the tallest known cliff in the solar system: Verona Rupes, a 20 km fault scarp. At more than 8% of Miranda's radius, an equivalent cliff on Earth would be over 300 miles tall: bigger than Miranda itself! I think the APOD is a zoom and crop of this image, which shows how completely disrupted the terrain is in the neighborhood of that enormous cliff.

I commented to Dana in a recent note, that in each page I had found worthwhile reading while brushing up on this topic, I was amused to see some variation of the comment, "...but, really, no one knows for sure." When I was young, in middle school, I was under the impression that essentially all the questions in science had been answered. And while I loved science, I didn't really grasp what scientists *did,* beyond just "knowing things." Without that context, I don't suppose you'd be able to grasp the childlike glee that the phrase "...but, really, no one knows for sure," gives rise to in my heart. Knowing is wonderful, but coming to know is even more wonderful. And recognizing what one does not know is the first step in that process.

New Horizons is on its way to Pluto, with passage through that system expected in 2015. Based on the Voyager missions, as well as innumerable other planetary science missions over the last few decades, I have no doubt whatsoever that there will be things there that will blow me out of the water. But I will always have a special fondness for Miranda, a tormented child of the the solar system. There are no further missions planned to Uranus, and it's unlikely any great strides in understanding exactly what caused that chaos will occur during my lifetime. I'm okay with that. I wouldn't want to live in a universe where's there's nothing to point at, and with a note of wonder and awe, say, "...but, really, no one knows for sure."