At this point in my life, I’ll admit it’s highly unlikely I’ll ever make it there, but if I do, you can all expect a spectacular GigaPan.

One of the keys to a longer lasting Schott Rule-free competition is selecting localities that are obscure or well enough disguised to not be immediately locatable, yet not so obscure that they cause the hunters to gnash their teeth and desire to claw out their eyeballs from fruitless searching for hours and days on end. It is particularly challenging to choose a spot that meets these requirements and yet maintains an element of geologic distinctiveness. I think I was able to do that with WoGE #338 at Cape Royds, Antarctica. Only time will tell if I’ve duplicated the feat with WoGE #341 below.

Locating the image below in Google Earth is your first task. Once you’ve done so, you must next determine the geological significance of the locality. The first person to successfully identify both location (latitude and longitude, please) and geological significance in the comments of this blog post will earn the honor of hosting WoGE #342 on their own geoblog.

.

No Schott Rule. Dig in!

I know the WoGE hunters will be eager to get started on their next expedition, so with no further ado (and no Schott Rule) I present the target of your next search in the image below. As always, the person who correctly locates it (latitude and longitude will do nicely) and describes the significance of the geologic features seen therein will then reserve the honor of posting WoGE #339, in turn.

.

What are you waiting for? Mush!

So here goes nothing…

I don’t think anyone has claimed Accretionary Wedge #44 for March 2012 yet, so if you’ve been waiting to host one this may be your opportunity.

.

During my summer internship at the USGS in Menlo Park, CA in 1996 I became familiar with more recent works of cartographic art, such as the oblique illustrations of geological phenomena in the Sierra Nevada by Tau Rho Alpha (yes, that’s his name). See some of the figures in The Geologic Story of Yosemite National Park (1987) by N. King Huber, for examples of his work.

Nonetheless, from the moment I suggested this theme for an Accretionary Wedge there was really only one figure I gave serious consideration to selecting as my favorite geological illustration. And that is Figure 5 (at left) from the 1877 printing of Grove Karl Gilbert‘s Report on the Geology of the Henry Mountains. Captioned “Ways and Means,” the hand drawn illustration of a mule’s head is a reminder of the remote nature of the Henry Mountains – the last significant region of the conterminous United States to be explored and scientifically documented – and the realities of fieldwork in the mid-1870s in the West. The figure is actually a partial reproduction of a sketch of the mule “Lazarus, Duke of York” (reproduced at right) that Gilbert himself sketched in one of his own field notebooks. What draws me to this image even more, however, is that it was removed from the second (and much more widely circulated) printing of this famous report (though I was fortunate that UW-Madison had a first edition in its library collection when I was a grad student there). I learned the history of this figure through the scholarly work of Charles B. Hunt (of ‘cactolith’ fame), in his “Geology of the Henry Mountains, Utah: as recorded in the notebooks of G.K. Gilbert 1875-76″ (Geological Society of America Memoir 167). Hunt raises the possibility that the figure was cut to save printing costs, but suggests that resetting the rest of the type would have likely had the opposite effect. I prefer to think that some humorless editor gave old Lazarus the ax, in an effort to make the report more professional looking (it was, after all one of the first USGS Professional Papers). I’d like to think G.K. Gilbert would have enjoyed publishing about his work and travels in a less formal medium, such as the geoblogosphere. I certainly feel that modern geologic communication could use some of the more personal, humorous touches of which “Ways and Means” is symbolic.

What I want to push back on here, though, is the term that Callan coined for these samples, “xenobomb”. Though the samples of this type from cinder cones could arguably be called volcanic bombs, the samples cited by Callan and Siim lacked the streamlined features of a true lava bomb. In fact, I’ve seen a spectacular sample of a xenolith-cored lava bomb, complete with a beautiful aerodynamic basaltic bomb coating in the petrology lab collection of the University of Wisconsin-Madison (sadly I don’t have a photo). What really irks me about “xenobomb” is not the shape of the particular samples that Callan and Siim used to define it, but the etymology of the word. “Xenobomb” suggests a “foreign” bomb. That’s just not what these samples are. Perhaps in their new lab environments they’re xenobombs, of a sort, but on the volcanoes where they were collected “xenobomb” suggests bomb pieces that are foreign to the eruption from which they originated, and that’s just plain wrong. Plus, I’d hate to think of the cinder cones that formed them as xenobombers – can you imagine the hatred that would be heaped on them by American politicians? Before long there’d be campaigns to rid America of the xenobombers and innocent cinder cones like Wizard Island and Sunset Crater could be swept up in the hysteria. Words have meaning – use them cautiously.

Could this be the end for innocent cinder cones?

I’ve been fairly fortunate in my time as a geologist to witness a volcano erupting firsthand in Hawaii. If I tried to tell you that I’ve directly experienced a more memorable geological event (at least to this point in my life), I’d be lying. I’ve also had the chance to feel a couple of very small earthquakes firsthand in New Jersey (Ramapo Fault), Hawaii (Kilauea Volcano), and Kansas (Oklahoma quake that triggered this Accretionary Wedge topic). I slept through an even bigger quake (M7.3 Landers, ~150 miles away) during my first field season, and saw the damage firsthand before the day was out. This past spring I saw the Mississippi River at a record flood crest from the safety of the levee near the Old River Flood Control structure and drove across the Morganza Spillway with 19 gates open, sparing New Orleans from another watery apocalypse. These last two may have been the most significant geological events I’ve witnessed firsthand. Nonetheless, the event I’m choosing to write about is a different event altogether.

The geological event that is the focus of this post is the Nardi Road/Goulais River landslide of October 13, 2003. Although this event was of a more local scope than some of the ones I enumerated above, I was able to witness firsthand the profound consequences for those who experienced it most directly. I was fortunate to be able to see and document the consequences with my Geoenvironmental Systems class less that 24 hours after the slide occurred. Mr. and Mrs. Norlin, whose safely rode out the slide in their red-roofed house (which features prominently in a number of images below, were kind enough to grant us permission to examine the slide in firsthand detail, and it must be noted that their spirits were remarkably good, despite the ordeal they had so recently survived.

Norlin House and Suburban

.

For the most part, I’ll let the pictures do the talking – the full set of images can be seen on Flickr. The immediate triggering event for the landslide (or more accurately, a rapid, progressive series of rotational slumps) is unclear and may never be known. In a larger sense, this area was located on a cutbank of a meandering section of the Goulais River. The slump was rooted in a thick sequence of varved clays deposited at the end of the Wisconsinan Ice Age, as well as alluvial sands. There have been a number of other slides of this type in the region historically – in fact, our class had already examined the deposits of one such slide on the south shore of the Saint Mary’s River just a few miles west of Sault Ste. Marie, MI earlier in the semester. Although this event took place long before I had my first GigaPan, I did already own my first digital camera, and I shot a number of panoramic shots along with the many individual images seen below.

Dennis Guimond’s House, next door.

.

The Norlin’s House and a shed

.

The Goulais River, near the toe of the slide.

.

Location of the Nardi Road/Goulais River Slide (Google Earth)

.

Evolution of the Landslide Toe, April 2005 – May 2007 – March 2010

.

Varved glacial clays are visible in a crevasse beneath a thin mantle of sand. Detachment surface is locally dipping about 45 degrees. Faint “slickenline”-like traces were still visible in the loose sand on the detachment surface in the days immediately after the slumping event.

.

Tension gashes formed in the “lower plate” of this detachment surface within 24 hours of the main slip event.

.

Kelsey Anderson points out a normal fault where the “lower plate” of this detachment surface (now horizontal) has been offset within 24 hours after the main slump event.

.

General Chaos and Mayhem, LSSU students for scale.

.

High angle detachment surface near headwall. Note slip direction on the detachment surface is delineated by sand and soil still coating the muddy surface. Varved clay sediments make up the footwall of this block.

.

Headwall of the slide complex. Sandy alluvial sediments and soil make up the highest layers; varved clays are lower down. The Suburban had been parked outside the carport and buried itself vertically during the event. Geology students for scale.

.

Slicklenlines and boot prints in the lower portion of the slide.

.

Detachment surface and varved clays near the headwall of the slump.

.

Evidence for late-stage lateral shearing. These horizontal slickenlines were formed as a cluster of maple trees was dragged laterally toward the end of the slide sequence.

.

Trace “fossil” where a tree trunk indented the varved clay sediments of this block.

.

Tree trunks with clay from the impact above.

.

The “Birch Tree Block”

.

Another great day in the field.

.

You can also consider this the final call for submissions for Accretionary Wedge #41. I’ll be writing up the summary post next (tomorrow).

A reminder that the Geology Office Hours hangouts are now on holiday break. Next one is scheduled for Thursday, January 5, 2012.

After last Thursday’s hangout +Brian Schrock commented: “Maybe we could do an office hour sometime regarding grad school for us undergrads. I always seem lost in the grad school process despite all the help my professors are giving me.” I think that’s a great topic for one (or more) of these hangouts, so I’m designating it as the primary topic for this Monday’s hangout. Ideally I’d like to have a couple of other geology profs and/or current grad students share their experiences and insights, in addition to as many undergrads with questions as possible. I’ll plan to record the Hangout for those that can’t make it. Also, if there’s enough interest, possibly we’ll repeat this topic sometime in the new year.

For those interested in participating, you’ll need a Google Plus account and a computer (desktop/laptop/Android smartphone), ideally with either a built-in or USB webcam (I’ve had great results with a Logitech 720p Webcam Pro 9000). If you haven’t done a hangout before, read up on Hangouts and make sure to install the required Google Talk add-ons ahead of time (you’ll be prompted to do this).

Finally, I’m going to take a two week break for the holidays from my regularly scheduled hangouts after Monday’s hangout. If there are big geological events in breaking news I may hold an ad hoc hangout or two, as necessary. Otherwise, hangouts will resume on Thursday, January 5, 2012.