Tuesday, May 6, 2014

Where are the Ten Most Incredible Places You've Ever Stood? My Number 5: Walking in the Footsteps of James Hutton

This entry into my series on the "Ten Most Incredible Places I've Ever Stood" is sort of a two-for-one deal. It was my journey into a different kind of geological past, the history of the science rather than the history of the world, although that was part of the story too. This was a visit to the birthplace of geology as a science, at two locations in Scotland.
"What clearer evidence could we have had of the different formation of these rocks, and of the long interval which separated their formation, had we actually seen them emerging from the bosom the deep? We felt ourselves necessarily carried back to the time when the schistus on which we stood was yet at the bottom of the sea, and when the sandstone before us was only beginning to be deposited in the shape of sand or mud, from the waters of a superincumbent ocean. An epocha still more remote presented itself, when even the most ancient of these rocks instead of standing upright in vertical beds, lay in horizontal planes at the bottom of the sea, and was not yet disturbed by that immeasurable force which has burst asunder the solid pavement of the globe. Revolutions still more remote appeared in the distance of this extraordinary perspective. The mind seemed to grow giddy by looking so far into the abyss of time...."

These are the words written by John Playfair as he described an extraordinary boat journey he made with James Hutton in 1788 to Siccar Point, a spot where Hutton found confirmation of his model of the Earth's development. At the point, Silurian graywacke sandstone layers (425 million years old) stand nearly vertical, and are overlain by bright orange and brown layers of the Devonian Old Red Sandstone (345 million years). Such features are called unconformities. During the interval of time before the deposition of the Old Red Sandstone, the sea floor had been compressed and thrust upwards into a mountain range that was subsequently eroded completely away. Such events required the passage of vast amounts of time, something quite incompatible with the mere 6,000 years of Earth's existence assumed by medieval religious scholars. Hutton's explorations of Scotland ignited the revolution that led to the development of the science of geology.

In 2001 I had the chance to visit some of Hutton's most famous rock exposures. We had put together our very first international field studies journey to England and Scotland, and being unfamiliar with the territory, we had contracted with a tour company to take care of the logistics. We got a canned tour of the famous tourist localities like Stonehenge, Big Ben, and Edinburgh Castle, but we made special arrangements with the tour company (for a price) to deviate from their usual itinerary (we missed the golf courses of St. Andrews) so we could instead head into the southern uplands of Scotland to Siccar Point. We committed to the trip 1 1/2 years in advance, having no idea that hoof-and-mouth disease was about to be detected in the British Isles, including the farms around Siccar Point. To my almost unspeakable frustration, access was impossible. Not wanting to just give up, I pulled out the topo maps and we made our way to a campground on the coast about a mile north of Siccar Point. I read the passage from John Playfair to the students, and than I ran as far as I could along the beach cliffs to where I could see the point, but not the relationships (although we could pick up the associated rocks along the coast).
The idea of unconformities and the concept of geological time would have been enough to secure Hutton's reputation as a geological pioneer, but he made another profound observation in the middle of the city of Edinburgh. That was the second spot I was seeking on this geological pilgrimage.

For years I've been showing a video to my students on the development of the theory of plate tectonics. It was done in the early 1990s but has held up well aside from the ancient computers in some of the scenes. It begins in Edinburgh with a look at the Salisbury Crags and Arthur's Seat, where James Hutton discovered an ancient volcano that once sat on the sea floor. Other observers in these early days of geology thought that basalt accumulated on the sea floor by precipitating out of the water, much like salt deposits in a drying bay. Hutton found a contact zone in a small quarry at the base of the Salisbury Crags where the intruding basaltic rock had pried up the previously existing sedimentary layers forming a vast sill. In other parts of Scotland he found intrusions of granitic rock that had done the same thing. In short, he had discovered intrusive (or plutonic) igneous rocks, and opened our eyes to an entirely different way of considering our planet, an active planet with an internal heat source, and cyclical processes that had been operating for millions, not thousands, of years.
I didn't have much of a clue about how to find the quarry, but sunset came late in our northern latitude, so after dinner I set out from our hotel and walked to the crags. It didn't actually take very long before I found a concrete monument and the very exposure that had been illustrated in Hutton's early books. It was a marvelous moment in my geological life (and a great sense of relief because I was going to be showing it to my students the next morning and had to pretend I knew where it was all along).
The big adventure of the next day would be the climb up to the summit of Arthur's Seat, the eroded and glacially scoured volcano that had once been in an ocean. The peak is surrounded by the city of Edinburgh, and was originally preserved as a deer hunting park for the king, but more recently because of a number of rare plant and animal species, as well as being a bit of greenery in an urban setting.
The peak is an archaeological treasure with the remains of ancient fort at the summit, and the ruins of a chapel, St. Anthony's, built in 1425 on the flanks. It was such a strange sight for the middle of a city.
Although it was a bit hazy, the whole city was visible from our 822 foot summit. We could sit on our "throne" and consider the volcanic eruptions that built up the volcano, the continental collision that deformed and tilted the rocks, and the glaciers that scoured the flanks during the ice ages of the last two million years.
Do these pictures look a little fuzzy, a bit low of resolution? There's a story there. I had heard of digital cameras, but they were expensive and I couldn't fit them in my budget (my, how times have changed...). Because the Scotland trip was a major event for our department, I convinced the administration to spring for a modest camera (an entire 3 megapixels!), and it arrived in Shipping and Receiving late in the afternoon before our departure the next morning. When I got on the plane, I had taken and downloaded all of three images. I barely knew how to use the camera, and didn't really trust the technology, so I ended up mostly taking lower resolution pictures. I would never make that mistake again, but such is the learning curve. At least I didn't accidentally delete them all like I've done on a few other occasions. If you would like to see some very excellent and more recent pictures of Arthur's Seat, check out this recent post at Magma Cum Laude: http://blogs.agu.org/magmacumlaude/2014/04/06/edinburgh-arthurs-seat-and-salisbury-crags/
Not many people in Edinburgh know of James Hutton, and his role in the development of the science of geology. Mostly I got blank stares when I asked directions to the monument. James Hutton is buried in Edinburgh and we paid a visit to the cemetery, but they had to pull out a catalog to find out where he lies buried. The section of the cemetery where he is interred was locked and chained, apparently because of continuing abuse by leaders of the popular ghost walks of Edinburgh (yeah, I took one too, but aside from atmospheric fog in the streets I was unimpressed).
Hutton's resting place is on the left side of this yard.
How much does the average person know about Scotland and England? That there is a queen, and the men wear kilts. We of course realized that we weren't going to be seeing any queens, and it was silly to think that all the men in Edinburgh would be going around in kilts. Except that both of those things happened!

As we made our way down the road towards Arthur's Seat, we noticed that nearly every man on the street was wearing a formal kilt, and we wondered why. As we approached Holyrood Palace, we realized that everyone was gathering for a "garden party" hosted by Queen Elizabeth. There were just a few people in attendance, about 8,000 of them. From our vantage point on the flank of Arthur's Seat, we could pick her out, wearing a blue outfit in a receiving line next to the side of the building just slightly left of center in the picture below. Yes, it was a crazy, unique day.
Just to accent the weirdness, we passed the street sign below. It wasn't actually a prophecy, but instead was an alleyway (a 'close') on the edge of the old city, which was the edge of the world to the medieval inhabitants.
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