Accretionary Wedge #63 AND Berry Go Round, Two Blog Carnivals and One Post on Serpentine

I don't usually post two blogs in one day, but the latest Accretionary Wedge deadline is approaching, and I'll be on the road again, doing Christmassy things with my family, so I might not have a chance later on. Our host of the double carnival is month is Hollis at In the Company of Plants and Rocks. The topic for both carnivals is as follows: Plants and Rocks (or Rocks and Plants). 

Reading the rather wide-open topic immediately brought to mind a subject dear to my heart, the state rock of California and a group of beautiful minerals: serpentine. There was a bit of political controversy a few years back about serpentine and its past use as a source for asbestos, and I did quite a few blogs on the subject. But even earlier I had written a blog post for my Other California series that explored the little known but geologically interesting areas of California, the ones that rarely showed up on tourist postcards. These are the kinds of places you seek out when you've seen the Golden Gate Bridge and Yosemite Valley. I am rejuvenating a post from the series, one I wrote about the Red Hills in the Sierra Foothills near Jamestown and Knights Ferry. It first appeared on March 27, 2010, and is mostly reproduced here with minor changes. It was titled "There's an Endemic in those Hills!" Oh, that's right, it's epidemics we're supposed to worry about. An endemic refers to plant species found in specific limited locations. There are a number of these in the Red Hills "Area of Critical Environmental Concern", a rather high-falutin' name for an area that less than two decades ago was barely more than an open garbage dump scarred by numerous off-road vehicle trails. The rare and endemic species are there for a very geologic reason, the subject of this post.

The Other California is my continuing blog series on those places in California that people don't generally find on the postcards at all our tourist traps. I've been following a regional theme, traveling through the northernmost provinces, but the Other California has a temporal pattern as well, and late March is the perfect time to talk about the Red Hills, located in the Sierra Nevada Mother Lode near the Gold Rush town of Chinese Camp (I talked about the area around La Grange a few days ago for the same reason).

Much of lowland California is currently covered with a green carpet of grass (mostly of exotic and invasive origin) along with the occasional oak tree, but as you can see in the pictures above, there are a few places where the grass and oak trees are missing, and a profusion of flowers and scattered pines thrive instead. Why are the oaks and grass missing?

The Mother Lode is famous as the source of the ores during the Gold Rush in 1848-53, and many people know of the association of quartz veins with the gold. What is perhaps less known is that the Mother Lode consists mostly of metamorphic rocks like slate, greenstone, and marble, not the granite that is found in the higher parts of the Sierra Nevada. These metamorphic rocks are the twisted and baked remains of sea floor muds and silts, lime from tropical reefs and shelves, and volcanic rock from the oceanic crust. These collections of crustal rocks (called "exotic terranes") were transported across the Pacific Ocean and slammed (in the geologic sense; they moved at maybe 2 inches a year) into the western edge of the North American continent, mostly in the late Paleozoic and Mesozoic eras (the Mesozoic, from around 251 to 65 million years ago, is best known as the "age of the dinosaurs"). The different terranes are separated from one another by major fault systems.

At times the crustal terranes also include rocks from beneath the crust. This rock hails from the underworld of the earth's mantle, and includes dunite and peridotite, composed primarily of the mineral olivine (known to most people as the gemstone peridot). The rock readily alters to serpentine, California's state rock. These rocks are also collectively called ultramafic rocks, for their high content of magnesium and iron (fe, the 'fi' part). They also contain small, but significant amounts of nickel and chrome.

When ultramafic rocks are brought to the surface, they are far out of chemical equilibrium with the ambient conditions, which means they are easily attacked by oxygen, water and organic acids. Clay is a common product of this process, as well as red or yellow iron oxides (from which the Red Hills take their name). The surface layer resulting from this weathering process is of course soil. We tend to think of soil as a rich surface layer that supports plant life, but some soils lack the necessary nutrients for most kinds of plant growth. This is definitely the case for soils developed on ultramafic rocks, which lack nitrates, phosphorus, and potassium. To make things worse, chrome and nickel are actually toxins. Hence, only specialized species can thrive on these rocks.

The shrubby Ceanothus, or Buckbrush (above) and Gray Pine (below) are two plants that are more or less indifferent to the odd soil conditions. They grow elsewhere, but compete very well in ultramafic soils. A large number of flower species are also indifferent to the soils, but the only grasses found in the region are native species. The European and Asian grass species that have overwhelmed most of the prairies in the Central Valley, Coast Ranges and Sierra foothills cannot grow on the serpentine soils.

There are a number of endemic species that grow on these soils, and at least one is found nowhere else in the world (California verbena, Verbena californica). Other rare endemics include Rawhide Hill onion (Allium tuolumnense), Layne's butterweed (Senecio layneae), Congdon's lomatium (Lomatium congdonii) and the Red Hills soaproot (Chlorogalum grandiflorum). A fairly common serpentine endemic is the Milkwort Jewelflower (Streptanthus polygaloides). Alas, I arrived very late in the afternoon and had no time to search them out (and to be truthful, I am better at identifying rocks and minerals).

Though closely associated with the rocks of the Mother Lode, the serpentine and dunite were remarkably free of gold, and so the Red Hills were mostly ignored by the miners. Farmers couldn't grow much in the soils, and grazing conditions were not favorable, so the when the federal government came into possession of these lands in 1848, they couldn't even give them away! So this swath of land, about 7,000 acres worth, was administered, somewhat indifferently, by the Bureau of Land Management. The landscape suffered the abuses of modern civilization, with trash heaps, motorcycle trails, and unrestrained target shooting. The recognition that the area was a unique geologic and biologic treasure led to the restriction of shooting and off-road vehicle use in 1991. Private groups assisted in cleaning up the trash heaps and a trail network was established, so today the Red Hills are a delightful place to visit, especially in the spring when the wildflowers are at their stunning best. And I could be wrong, but I don't think I've seen any postcards with pictures of the area.

If you want to learn more, or pay a visit, information about the Red Hills can be found on this BLM website , and the nature trail brochure PDF can be found here.

There Will Be Signs: This Month's Accretionary Wedge!

This month's Accretionary Wedge, sponsored by Evelyn Mervine at Georneys, is on the subject of geology-related signs. The subject is a good one, and it rang a little bell in my memory circuits; I remembered doing something on signs a LONG time ago, during the early Mesozoic era of geo-blogging, circa 2008. I did a little digging and came up with this post from March 6, 2008 (only two months after starting Geotripper):

Soon after posting a few death-defying pictures, Julian at Harmonic Tremors posted an additional photo of an "Unsafe Rock Area" (Danger danger danger! ), which brought to mind two of my favorite geology-related caution signs...the picture above is a sign warning of falling rocks at the base of a 400 foot "cliff" in southern England called Salisbury Cathedral!

The other sign may be familiar to travelers at Hawaii Volcanoes National Park. Just in case anyone feels uncomfortable passing such a sign, the park was kind enough to announce....

2013 addendum: I later found out that the "fault zone" in question suddenly split open a decade or two ago (in front of a geologist), and a short episode of lava extrusion and flow ensued. Then it stopped and has been quiet since.

Accretionary Wedge #56: Because Every Picture of the Earth Tells a Great Story

Andrew Alden at About Geology is hosting this month's Accretionary Wedge, and the topic is landscape topography through the eyes of a geologist:  

Once upon a time, you took a picture of something that lots of people photograph. However, because you are a geologist, it didn’t turn out the way it does for most people. Show us that picture, tell us what you see in it, and tell us about the way you take pictures.

No matter where you go, no matter where you are, there is a story to be told by the rocks. And ultimately, no matter how dull the scene might appear, the story is fascinating. These are the first words that I utter in every class I teach, and I cannot look at a landscape, any landscape, without wondering what lies beneath. And sometimes the scenes are far from dull.

To many, the story to be told by a picture may be "I was standing in front of some scenery". Few geologists can ever see a landscape that way. The picture above is one of my favorites, because such a rich history is encapsulated in the small frame of the photograph.

We are standing in a small arch located in Arches National Park in Utah, which actually happens to be called Frame Arch. The view extends across the fault graben of Salt Creek Valley to the distant La Sal Mountains. The reddish rock is the Entrada Formation, a sandstone deposit that developed in the tidal zone of a coastline in Jurassic time. Dinosaurs once climbed coastal dunes in this spot where I stood snapping a picture.

The rocks are tilted because there is a huge body of salt beneath the surface. Water trickling down into the fissures and joints dissolved away the salt near the surface, and the Entrada layers collapsed into the void.

The La Sal Mountains in the distance are volcanic, or to be more correct, laccolithic. The high peaks are made of the more resistant rock that squeezed between and inflated the space between sedimentary layers. Later on, the rocks were lifted up and the overlying layers were eroded away. The eroded mountains are the hearts of ancient volcanoes.

How did this photo "turn out different"? It's because I was more or less ignoring the reason this opening in the rock was called Frame Arch...just to the left in the distance, you can see the slightest opening to what may be the most famous arch in the world, Delicate Arch. It's the symbol of the park, and almost everyone climbs up to Frame Arch uses it to frame Delicate (below). But the geologist's eye takes in more than icons.

Thanks, Andrew, for hosting the Accretionary Wedge this month!

Accretionary Wedge #55: Blood on the Rocks, and Bad Karma on the Plateau

This month's Accretionary Wedge is hosted by Maitri at her Vatulblog, and it concerns our injuries incurred in the field: "Show me your injuries! ... You don’t have to be a geologist to play; simply having been injured by a rock or while doing something geological is sufficient. I will put the entries together and post them here as well as at the AW site at the beginning of March. The winner (one with the most spectacular wound or story) gets their choice of two bandage tins from this website mailed to them."

Actually, in twenty-five years of leading field trips, I have been remarkably (some would say eerily) free of serious injuries. Of course, by simply saying this I am bringing on the threat of geo-karma, and I will no doubt get bit or fall down a steep slope on my next trip. On the other hand, I have taken somewhere around 1,500 students on multi-day field trips, and some of them have managed to inflict a bit of self damage. Luckily, only a few required a trip to the emergency room, including a split-open chin, and a hairline fracture of a wrist caused when someone caught their fingers in a van door and wrenched an arm trying to pull them out.

The chin involved stitches after a fall on some rhyolite boulders in the Mojave Desert. From my point of view, it was my discovery of the accident site that was intriguing. I was trailing behind the rest of the crew in a deep cleft in the rocks, and I noticed the blood on the rocks (see the picture above). I stopped, looked around, looked up. In my ignorance, I assumed an owl had made short work of some rodent that night and was a sloppy eater. I continued on down the trail until some of the students came back and let me know we needed to make a stop in the emergency room in Needles, California.

The most famous injury during my time at the college was not quite so serious, a turned ankle, but it set in motion events later that day that have since become legend in our department. It involved rattlesnakes, and a suicidal deer (I originally blogged this story in 2008).

The rattlesnakes were simply an omen for the day. I and my students had set out on a cross-country trek to look for Ancestral Pueblo cliff-dwellings in eastern Utah. I stopped a moment and heard under my feet that buzzing sound that field workers don't usually like to hear: a rattlesnake. Only it seemed like it was in stereo. I looked down and saw not one, and not two, but three rattlers between my legs. I should have known right then to cancel the day and just go home, as I jumped through the air in some random and probably poorly chosen direction. No bites, but a very high heart rate for awhile....

Meanwhile, a deer had decided to cross the highway near Blanding and Monticello. That was still four hours in the future, though.

One of my students (who shall remain nameless for the moment) walked into the wilds, lacking water, companions, and common sense. He wandered off the mesa, climbing down a 4oo foot cliff, and climbing onto the adjacent mesa. He hadn't heard anyone for several hours and finally realized he was lost, and was long overdue at the vans. He tripped and fell, wrenching his ankle badly. Back in the parking area, concern was growing and search parties were organized. Finally, two hours later, as we prepared to contact the local Search and Rescue, our lost student stumbled out of the pinyon forest, having heard the honking of horns. We were now two hours behind schedule. We set out on the highway, headed to Blanding and Mesa Verde. And a few minutes after that, a deer, hidden completely by a concrete embankment, chose that moment to cross the busy highway.

We should have passed the embankment along the highway two hours previously, but our student  had been lost. And so we were selected, involuntarily, to introduce the deer to the hereafter. And the front of our van would never again be the same. We were, in fact, alive only because of the expert emergency driving skills of our professional volunteer, who managed not to turn us headlong into the big truck in the opposite lane as the collision occurred.

That's geo-karma...

A final note:

This wedge entry and others like it are a light-hearted look at what turned out to be fairly minor injuries. Such injuries have a potential to become major injuries in the isolation of the field, and major injuries have the possibility of becoming life-ending situations. There is no getting around the necessity of being as safe as possible when conducting field work. I can think of no situation worse than having a student die while under my supervision.  Someone passed away during a recent conference (from a long-term medical condition) we sponsored in an isolated mountain location. The staff at the conference center and our volunteers acted professionally and quickly, but nothing could be done. It was tragic beyond words.

If you are responsible for the students or fellow researchers, hold them to the highest standards of safety, and always have first aid kits available, and the training to use them. Don't allow a moment of fun taking a bit of a chance turn into tragedy.

Geopoetry: Accretionary Wedge #51

It's already almost the deadline for the Accretionary Wedge #51. Where does the time go? This month's wedge is hosted by Matt Herod at Geosphere, and the topic of the month is geology and poetry. Specifically: "In this wedge I encourage people to wax poetic about anything geological they would like, in any poetic style. Be it limerick, haiku or sonnet. Of course, you don’t have to write your own poem if that is not your thing. Find a geology/earth themed poem that already exists and explain why you like it and what about it moves you. So lets all connect to the bard hidden within us and slam out some great poetry!".

Geology and poetry aren't usually associated with each other, although the word "poetry" played a big part in one of the more important research papers of the 1960s: the Harry Hess paper that laid out the basics of sea-floor spreading and divergent boundaries ("History of Ocean Basins"). In his introduction, he referred to his work as "geopoetry", in that his ideas were speculative, but based on science just the same. He expected the confirming evidence would emerge later on, as it in fact did.

I'm not much of a poet, but my students have put together some great stuff over the years. One of my favorites appeared on my desk in my second year of teaching, back in 1990. I offer it as my contribution to this month's Accretionary Wedge...

The Ballad of Historical Geology by Vicki

Winding our way through geologic time
Has been quite an experience
Learning about critters long ago dead
from fossil evidence

Crumping, crunching orogenies
Adventure beyond compare
Transgressions, regressions, climatic extremes
If we could only have been there!

Or better yet, time lapse photography
To show us what occurred
From way back when in the Cambrian
When life forms were so absurd

Our list for field trips has expanded
We're poised, rock hammers at our side
Let's go find that Burgess shale
And some giant trilobites

Archimedes, archaeopteryx,
Let's go from A to Z
And collect all that we can carry
of every fossil family

Let's check out that iridium layer
In our search for ultimate truth
Or did the dinosaurs really die
From drinking tainted vermouth?

Now the semester has drawn to a close
We're all ready to go
But there is one thing we haven't addressed
That I'd still like to know

The text mentioned Lucy
But it did not discuss
Fred and Wilma, Barney and Betty
And their importance to us!

And where the heck is Bedrock
On Pangea I or II?
Could I get a map to go there?
If so I bid you adieu!

Well, Vicki...I found Bedrock for you in 2011. It's in the borderlands between Colorado and Utah in the Paradox Basin. The picture is above...

Accretionary Wedge 50: Bad Karma or the Giant Spaghetti Monster? Microburst at Grand Tetons

Evelyn Mervine at Georneys is the host of this month's Accretionary Wedge, and the topic is a delightful one: Share a fun moment from geology field camp or a geology field trip. You can share a story, a picture, a song, a slogan, a page from your field notebook– anything you like! Thanks loads, Evelyn...how to choose from 30 years of geological journeys??? If you have followed my blog at all, you know it is mostly stories from the road. So how to choose? I finally settled on the story that convinced me that the Giant Spaghetti Monster must really exist, or at least some level of karma...

It was a while back, in the 1990s. We were on our way to Montana to assist at a dino-dig at the original discovery site of the Velociraptor cousin Deinonychus. Excitement was high, as this took place right after Jurassic Park premiered, and we were working at one of the excavations directed by Jack Horner. It was a long drive, and we stopped for a night at Grand Tetons National Park.

What happened that particular evening became one of our department legends. One our students had a knack for fomenting trouble with the powers-that-be in the Universe. On various previous trips he had speculated about what it would be like to get stung by a scorpion, and within a day, he had been (unwillingly) stung by a scorpion. At a stop, he asked if we would see any rattlesnakes. He stepped on one moments later. There was a karma that hung about Craig like a hangman's noose.

There was a discussion that evening at Grand Tetons in the twilight about whether we would experience any bad weather on our journey. The skies were clear that night with just a few puffy clouds about. For some reason, Craig looked towards the heavens, raised a rock hammer towards the sky, and said "I dare the gods to make it rain!". I'm not kidding about what followed. Within ten minutes of his brash statement, our campground was enveloped in a violent storm, our vision obscured by thick blowing dust, and high winds were knocking down old cottonwood trees all around us. Fifteen minutes later the winds died, the dust cleared, and the camp was a shambles. Tents were ripped apart, and branches were down all over our camp. Our vans were undamaged, but a tree had crushed a van in the other part of the campground (people were in it, but were unhurt). We thought we had been hit by a tornado, but more likely it was a microburst from a storm that approached us unseen from the east.

Needless to say, Craig spent much of the rest of the trip muzzled....but this is not the only Craig story. The other involved rattlesnakes, deer, and a lost student. If you are interested, it can be found here....

Accretionary Wedge #49: It's just out of this world! Hollywood and the Cosmos

It's time for an Accretionary Wedge! Specifically Wedge #49, hosted by Dana at En Tequila es Verdad. The topic is essentially anything exogeologic, that is, beyond the confines of planet Earth. I'm taking the broadly interpreted topic and turning my contribution into a quiz.

Lots of Hollywood movies take place in space and on other planets, and since the director can't go to the other planets, locales on Earth have to suffice. As geologists know, there are landscapes on our planet that do a good job of looking otherworldly, and so geology became a central part of the movie plot.

Sooo....how well do you know your planet, and how well do you know sci-fi movies? Name as many localities as you can in the pictures below, and name the movies in which these landscapes starred.

1) Sand dunes and dark ridges in the distance....

2) A very deep valley in a dry place....

3) Very strange knobs of sandstone...

4) And more sandstone. All the action took place among the red rocks in the foreground. A famous captain bought it here....

5) A glacial lake and alpine peaks...

Picture by Doug Dolde (http://en.wikipedia.org/wiki/File:Ghosts_of_Trona.jpg)

and 6) Some strange towers of calcium carbonate...

And what places did I forget? What would you add to a quiz like this?

When Life Got Complicated: the Burgess Shale (Accretionary Wedge #45)

Life as a Geologist is our host for Accretionary Wedge Carnival #45. And what a great topic:
"Geological Pilgrimage – the sacred geological place that you must visit at least once in your lifetime ....a single place, which is “geologically” unique, relatively remote, and requires some difficulty to get to. If you have already done your geological pilgrimage, please share with us your experience..."

I've had a rich life, being able to link my favorite activities, traveling and photography, with my career as a geologist and teacher. It means I have been to a lot of places, so a topic like this leads to a lot of introspection. I'm also looking forward to reading some of the other entries...I like new ideas of where to go!

I thought of a lot of places, but I settled on one particular site because of the emotional impact it had when I reached the goal. It was indeed remote, and was difficult to get to. It was the Burgess Shale fossil quarry in Yoho National Park in British Columbia, Canada. Besides being one of the most important fossil sites in the world, it involved one of the most beautiful hikes I've ever taken. Just look at the scenery from the edge of the quarry:

Fossilization is a chancy process. Everything has to happen just right, and most of the time organisms are immediately scavenged or quickly decay. Even when things happen just right, it is exceedingly rare for anything besides bone or shell to survive. As a result, the fossil record is highly biased towards creatures with shells. When one considers how many soft-bodied creatures exist in the world's ecosystems, and how rarely they are preserved, we realize how poor our picture of the past really is. This is especially true of the "dawn" of complex life in the Cambrian period, just over 500 million years ago. Something 75% of the record is made up of the various species of trilobites, and most of the rest are sponge-like archaeocyathids and brachiopods (simple bivalved creatures which are not as "advanced" as clams). Although we know that plenty of soft-bodied forms existed, they have not been preserved, except in a precious few places.

One of these is the Burgess Shale, in British Columbia. The shale accumulated as masses of mud slid into oxygen-poor water. The organisms living in the environment were killed immediately, as were the scavengers and microbes that would have consumed them. The outcrops were discovered by Charles Walcott in 1909, and over the years tens of thousands of specimens have been collected and analyzed. The rocks were full of diverse and sometimes bizarre species that would have otherwise been lost to all time (see this article for examples).

The Burgess Shale is high on a ridge in the Canadian Rockies, and it is a tough six mile hike to the quarry. As a World Heritage Site, and being within a Canadian National Park, access is highly restricted (and believe me, they know when someone is there illegally!). To see the quarry one must go with a conducted tour through the Burgess Shale Geoscience Foundation.

I made the hike in July of 2005, one of the first hikes that year in this cold alpine environment. The sun played hide and seek with the clouds, and rain occasionally threatened (I have the distinct impression that that situation occurs just about every day up there). Glacier Lilies were everywhere, providing a great deal of color along the trail. There were also several steaming piles of grizzly bear poop, so we stayed pretty close together on the trail...

It was a long uphill hike, but after 5 1/2 miles, we passed a sign that let us know we were drawing close.

I walked a little slower than the others, and I paused at the last few steps. Most of the other hikers were not geologists, and were only beginning to understand the importance of this site to paleontology. I gathered my thoughts and emotions, and stepped into the quarry for the first time.

It was still half-filled with snow and ice, but there were plenty of slabs of rock around. Trilobites were all over, and I almost immediately found a delicate sponge fossil. The others gathered at the far end of the quarry, so I walked over.

The foundation knows that random searching in the quarry will not reveal some of the rare creatures, so they keep some pretty decent samples in the red lockbox on the site. Gazing at the specimens, I realized all over again what a wondrous treasure this site this really is for paleontologists.

Collecting of course is not allowed here, but we were allowed to search among the slabs for fossils that we could "own" for ourselves through the magic of digital imagery. I quickly found a nicely preserved Haplophrentis, a primitive mollusk related to snails and clams.

My favorite find was a complex little Marrella species, which is actually the most commonly found fossil in the Burgess Shale. It was the most delicate fossil I've ever found. And hard to photograph!

I tried photographing the fossil from a couple of angles. The brown spot is a stain of fluids that escaped when the organism died. In case you are wondering, no, the specimen didn't "accidently" fall into my pocket. I put it in the pile next to the big red box, so look for it if you ever get up that way.

The rain started to fall, so we started down the barren slope. It's not a very smart place to be in a lightning storm! During the hike down, I was no longer so anxious about reaching the goal. I strolled along, enjoying some of the best alpine scenery I have ever gazed on.

Emerald Lake, thousands of feet below, really looked more turquoise in color, due to the fine clay particles suspended in the water. Glaciers are still carving these mountains.

After about ten hours and 12 miles on steep trails, I arrived back at the parking lot, tired but happy. It was indeed a place worthy of a geological pilgrimage.

Accretionary Wedge #42 "Countertop" Geology and the rock outcrops in downtown Venice

This month's Accretionary Wedge is hosted by Volcanoclast and asks of us the following:

Have you seen a great countertop out there? Sure, everyone says it’s “granite”, but you know better. Take a picture, post it on your own blog or send it to me and I’ll post it for you. Do you think you know what it is or how it was formed? Feel free to include your own interpretation and I’m sure others will enjoy joining in the discussion. Ron Schott suggested that we expand the entries by including any decorative stone material that has been separated by humans from it’s source. This includes buildings, statues, etc. There’s a lot of really unusual stuff out there, so make sure to find a good one.

So...my countertops are made of reprocessed clay (tiles, in other words) and are thus unremarkable, so I will take advantage of Ron's suggestion. I am offering up the picture above. Here's the story of where I found it...

Several years ago we took a class of geologists and archaeologists to Italy and Switzerland for a taste of overseas geology and culture. I didn't have the connections to do our own chosen itinerary, so we were on an arranged tour with a few geological diversions. We made sure we got to Pompei, and climbed to the top of Vesuvius (above), and in the best moment of the trip we managed to find the site of the original Alvarez K/T boundary near Gubbio (the first place where evidence was found for the asteroid that ended the existence of the dinosaurs). That is one happy (and VERY relieved) professor in the picture below. I more or less knew where the outcrop was located, but we missed it on the first pass with our large bus on the very narrow road, and we had to go several miles before the bus could make an Austin-Powers-style back-and-forth U-turn.

Still, we were on a tour, and in the middle stretches of the trip we explored the very beautiful towns of Florence, Verona and Venice. Spectacular, but not a lot of actual geology (although we had a lot to say about the mountains in the distance). I tried to convince our crew to go see the marble quarries at Carrara, but they insisted on seeing some badly engineered tower in some coastal town called Pizza or something like that instead (below).

It was in Venice that I found my contribution to the Accretionary Wedge. Geology-wise, the city is interesting because it is sinking, in part for being built on mud, and partly because of the tectonic environment (it is near a convergent boundary, and is being compressed downwards between two mountain systems). But by its very nature it has no natural outcrops of rock at all.

No natural outcrops, but plenty of rocks! The sidewalks and squares are covered with marble tiles from quarries in the Alps and Apennines. And as I was walking in the shade at the edge of Piazza San Marco (St. Mark's Square) I noticed unique swirls in some of the tiles: ammonites!

Ammonites were cephalopods related to octopi and the chambered nautilus that populated the seas in huge numbers during the age of the dinosaurs. It was nice to see these fossils in the middle of the urban environment of Venice, in a place so removed from their place of origin!

Accretionary Wedge Carnival #41: Geology in Progress...the night I got in big trouble

OK, not that kind of trouble. I wasn't falling off a cliff or getting buried in earthquake rubble or anything like that. I wasn't swallowed up by a lava flow, although that was a possibility if I had been more stupid.

This month's Accretionary Wedge is courtesy of Ron Schott and the Geology Home Companion, and he says: "Your mission, should you choose to accept it, is to relate the story of the most memorable or significant geological event that you’ve directly experienced.

What we seek for AccretionaryWedge #41 is an account of a geologic event that you experienced firsthand. It could be an earthquake, a landslide, a flood, a volcanic eruption, etc. (but don’t feel compelled to stick to the biggies – weathering, anyone?) – some geologic process that you were able to directly observe and experience."

Such questions certainly make you stop and think. I've been teaching for 27 years, and there were 8 years of college courses and tech work before that, so I have seen a great many places (as followers of this blog well know), but events? Not so many. I thought about the 1997 floods in Central California, when a 250-year flood nearly destroyed my in-law's mountain home. I thought of the three rock falls I've witnessed in the Yosemite area (story here, here, and here). I also thought about my first major earthquake, the 1971 Sylmar event. They were all important events, but their impact on my psyche was nothing like my encounters with lava in Hawaii.

I've had a somewhat rocky relationship with Hawaiian lavas, with some wonderful adventures and some real disappointments (and believe me, I wish I was there right now!). The ultimate adventure, though, was my midnight discovery of a new outbreak and ocean entry in 2006 that only five people saw, out of the thousands who had visited that week. Here's the story adapted from my post in June 2009:

"My third chance to see Pele's beauty came about in 2006 as a result of a family reunion that included a cruise of four of the Hawaiian islands. We arrived a few days early on the off-chance that there would be something to see on the Pu'u O'o flow that continued to erupt over the years. It had been a mostly quiet year, with lava flowing through tubes for seven miles before spilling into the sea.

I was not really expecting to see much. The problem is that the coastal cliffs around a lava entry are dangerously unstable. As the lava hits the water, it shatters and forms thick layers of unstable cinders, while being covered by lava flows. Every so often, the cinders slide downward, and the lava bench suddenly collapses into the sea. A number of people have been killed because they were standing on the benches when they collapsed. So, the national park service had erected a rope barrier to keep people from the most dangerous areas. Unfortunately, there was no view possible of the lava itself, according to reports. Just the bright orange glow of the steam rising from the turmoil below the coastal cliff.

These lava benches are killers! Photo courtesy of the U.S. Geological Survey

Still, it was worth a try. I told my wife and son and nephews that I would hike out, be safe, look at the glow of the invisible lava, and be back to the hotel by 9 PM or so. I took water, a flashlight, extra batteries, and my brand-new camera that I had bought that morning, and was just beginning to learn to use.

The hike was longer than I expected. There were so many people parked at the end of Chain of Craters Road that I literally had to walk an extra mile just to reach the trailhead. The flows were entering the sea two miles away, over trail-less pahoehoe flows. The sun set way too quickly and for route-finding I was down to my flashlight, and flashing beacons set up every quarter mile or so. Plenty of people were walking back with their flashlights, so the route was clearly evident. Most of the people I talked to expressed disappointment. Nothing to see but glowing steam. A few idiots who crossed the barriers. I was getting very tired. Pahoehoe may be smooth, but is still very uneven, and it only takes a single misstep to twist or break an ankle. I made it to the rope barrier, and could now see the glow and the steam. It was actually an awe-inspiring moment, as the moon had risen and was reflecting off the ocean behind the steam plumes. But no lava.

I realized that it had become very lonely. The only others about were four people in a party, and a flashlight off in the distance. I hung with the four people and a lady appeared out of the darkness. She suggested that we might want to walk to the far end of the rope barrier, another quarter mile away. And then she disappeared into the darkness again. I looked at my watch. Already 9:00 PM. I was going to be overdue. But, what was out there?

Curiosity got me, and I set off for the far end of the barrier. After 20 minutes or so, I surmounted a small cliff and looked down, and saw one of the most beautiful sights I have ever seen.

Needless to say, I was in a heap o' trouble when I walked into the hotel lobby at midnight. But I can never forget the incredible gift of that magical sight of lava pouring into the sea."

As I noted, my camera was purchased the very same day. I found out that it used batteries fast, and at the big moment I had to cannibalize my flashlight to take pictures. I was also learning the new settings, and I'm actually surprised I got any decent pictures at all. I also managed to get a short video of the flow just before it plunged into the sea...

Weird Geology: Accretionary Wedge #34...Our Human Nightmares

Well, how about that? I was trying to figure out how to squeeze in a bizarre shot from my recent trip to Joshua Tree National Park, and the 34th Accretionary Wedge announcement drops in my mailbox, courtesy of Dana at En Tequila es Verdad:

Geology can be strange. Outrageous. Bizarre. I'm sure you've all run into formations and landscapes and concepts that have left you scratching your head. Maybe they got less weird later. Maybe they stayed strange. But however transient or permanent that weirdness was, it got weird.

So tell us about it. Hit us with the strangest stuff you've got.

I'm late to the party, but what's new?I see a lot of weird stuff in my travels, but what strikes me isn't so much the geology, but our weird response to the geology. Can you look at the rock in the picture at the beginning of the post and not see the face of monster trying to emerge from the ground? The rock results from a random process of weathering and erosion, but see it from the right angle, and the rock becomes of mythical story of beasts and human nightmares and heroes on quests. Perseus fought Medusa, who turned men to stone. Tree molds in Hawaiian lava flows were people turned to stone (above). The volcanic necks of the Four Corners region were the monsters who were vanquished by the Navajo Twins Monster Slayer and Child-Born-of-Water (below).Pareidolia is a psychological phenomenon "involving a vague and random stimulus (often an image or sound) being perceived as significant. Common examples include seeing images of animals or faces in clouds, the man in the moon or the Moon rabbit, and hearing hidden messages on records played in reverse". It's part of being human, the recognition of human faces being one of the most important skills of a newborn baby.

Of course, such things can get out of hand when we start seeing Jesus on tortillas, or faces on Mars that are obviously signs of Martian civilization (I thought it was Elvis myself). Or the Devil smiling in the smoke and ash of the Twin Towers burning (wasn't there enough evil in the hearts of the terrorists?).

My Favorite Geologic Picture: Oh, so many to choose from...(Accretionary Wedge #32)

The Accretionary Wedge for early March is sponsored by Ann's Musings on Geology and Other Things, and we are asked for our favorite geological picture. What a hard choice!

Long before I had a digital camera, I used a particular slide from a trip in the 1980s to introduce my students to the idea of the fascination of geology. It was taken next to one of the most famous photography spots in our national park system, but it is not a picture of the iconic feature. It's the trail leading to it. Delicate Arch of the "Real" Jurassic Park lies just around the corner, and a crowd is often found there, especially at sunset. But I see fewer people stop and consider this scene....

I got into geology in part because of the wonderful journey of imagination that it is; a geologist is a world traveler, and a time traveler. The trail in this picture is formed on a natural break in the rock. Why is the break there?

In Jurassic time 180 and 140 million years ago, tidal flats and coastal sand dunes spread across this part of Utah. The surfaces of the dunes were pathways for all kinds of creatures, from insects to giant lumbering dinosaurs. The walked and crawled on these sands, and later the surfaces were preserved by subsequent layers of windblown sand. The surface later hardened a bit more than the others, and millions of years later, erosion exposed the old sands. A fracture developed along the surface, and the trail-builders of a few decades ago found it a great deal easier to just remove the overlying rock than to carve a new flat surface at great expense. And so it is that during our brief sojourn on the planet, we walk on the same surface, and perceive the significance of that fact. We use our minds to explore strange alien worlds, and yet these are the worlds that existed before ours and which became the raw materials for our own.
Again, practically everyone walks up to Delicate Arch, but there is another arch just a few steps off the trail that provides a stunning view the distant La Sal Mountains, the laccolithic cores of 25 million year old volcanoes. This picture, taken just a few yards from the one above, contains the four elements of ancient human thought: water, earth, fire and sky (the water is in the sky and in the creek below). The essence of earth science...

Thanks to Ann for sponsoring the Wedge!

UPDATE 8/19/11: Do you need geology-themed photos and images for teaching or research purposes? I have hundreds of geologic images posted at Geotripper Images. Check it out!

Accretionary Wedge Carnival #30: The Bake Sale

OK, I'm not a baker, I'm not a cake-maker, but I can eat with the best of 'em. This month's Accretionary Wedge, hosted by Callan Bentley at Mountain Beltway, is on a delicious topic, food! Educational food, no less...

I hereby challenge my fellow geobloggers (and any newbies who want to participate) to explore the interconnections between geology and food. This can take any form you want, but I’m really hoping for some edible, geologically accurate models. Yummy stuff that illustrates and informs about earth science? Yes, it is possible!

The end of the semester in my historical geology class is usually accompanied by a social gathering, and an interesting cake is usually in the mix. The picture above was a complicated mess befitting of the subject, an ocean-continent convergent boundary, i.e. a subduction zone. The brown is the region of a magmatic arc, where magmas rise to the surface forming a series of andesitic stratovolcanoes (the red glob on the right is the molten rock!). The yellow strip is the forearc basin, a shallow sea where sediments form thick layers. The only piece I can't make out specifically is the accretionary wedge, unless the blue is not ocean water (ironic, given the name of the carnival). I'm not sure how to interpret the rest of the layers, but I can report that they were tasty!

Edible education took a different turn a number of years ago when I had the chance to see Walcott's Burgess Shale quarry in British Columbia (one of my very first blogs was on the subject). The site is considered to be one of the most important fossil discoveries in the world as it yields up thousands upon thousands of soft-bodied Cambrian animals. This is important because usually only hard-shelled creatures are ever preserved. The Burgess fauna gives us a glimpse of the complete ecosystem that existed at the "dawn" of complex life around 510-515 million years ago.

As one might expect, the quarry is carefully protected, and collecting could actually land you in jail. So we thought it interesting that our guide promised that we would all get a trilobite of our own if we survived the six-mile hike to the quarry. The "trilobites" are below!