Uncomforming

 Oh, we won't give in

Let's go living in the past

Oh no, no we won't give in

Let's go living in the past

– Jethro Tull, Living in the Past

“After a time, you stopped tallying the specific hazards.  In its totality, the landscape was predicated on risk.”

To photograph an unconformity is to attempt to capture an image of nothing. You are not shooting a presence but an absence, a record of time that has been erased. It is a subtle and intellectual pursuit, one that begins with understanding the library in which you stand. The Colorado Plateau is that library, a 130,000-square-mile province of flat-lying sedimentary rock lifted thousands of feet into the arid air. The Grand Canyon is its primary archive, a book whose pages are strata, each one once the surface of the Earth. As geologist you know that every single horizon you see was a landscape in its own time. The story is all there, except where it isn't.

An unconformity is a gap in the geologic record. It is a surface, not a layer—a plane of contact where the rock below is vastly older than the rock resting directly upon it. It represents a period of profound erosion or a long spell of non-deposition, a time when the Earth, in this specific place, was taking away rock instead of putting it down. To the photographer with a certain kind of mission, these are the most dramatic scenes on the plateau. They are the scars of lost worlds.

Your eye must be trained to see them. Some are glaringly obvious. An angular unconformity is a story of tectonic violence and subsequent peace. You see tilted layers of rock, the evidence of an ancient mountain range, that have been sheared off perfectly flat, as if by a giant planer. Sitting on that flat surface are horizontal layers, deposited by a later, placid sea. The photograph must capture that relationship: the chaotic, angled energy of the old world capped by the serene horizontality of the new.

A non-conformity is a meeting of two entirely different classes of rock. It is where sedimentary layers—the sandstones, shales, and limestones born of water and wind—come to rest directly upon the igneous or metamorphic basement of the continent itself. This is the Vishnu Schist and Zoroaster Granite at the bottom of the Grand Canyon. To photograph this is to capture the contact between the surface world and the deep, cooked roots of the landmass.

The most difficult to capture is the disconformity, for it is the most subtle. Here, the layers above and below the gap are parallel. There is no tell-tale angle, no dramatic shift in rock type. It appears to be just another bedding plane, another page in the book, except that a geologist has read the fossil record and determined that one hundred million years of history are missing between the two seemingly contiguous layers. Photographing this requires context—capturing the named formations, the Redwall Limestone separated from the Tonto Group, and letting the caption do the heavy lifting. It is an image of a purely intellectual landscape.

To truly tell the story, the photographer must go to the places where these gaps are rendered most starkly. The first destination is, of course, the Grand Canyon, but not just the rim. The work is down in the Inner Gorge. You make your way to Blacktail Canyon, a narrow side canyon off the Colorado River. The source material notes this spot as uniquely accessible. Here, the story is not viewed from a distance of a mile but is available to the touch. The photographer can place one hand on the dark, crystalline Vishnu Schist, rock that is 1.75 billion years old, and the other hand, just inches above, on the coarse, brownish Tapeats Sandstone, which is a mere 525 million years old. More than a billion years of Earth’s history—a quarter of the planet’s entire existence, as some have calculated—is missing in that single handspan. The photographic challenge is to convey this temporal abyss. It is an exercise in texture and light: the way light catches the metamorphic sheen of the schist versus the grainy, sedimentary surface of the sandstone. The resulting image is a portrait of the Great Unconformity, a name given to this specific gap by Clarence Dutton in 1882. Ah yes, Dutton, more about him in a later post.

The Black Canyon of the Gunnison near Montrose, CO. The rock overlaging the basement rock, which forms the canyon, is Dakota Sandstone and Mancos Shale. This same basement rock can be found at the Colorado National Monument. Above the basement rock time is missing, the Mancos unconforms.

From there, the journey continues northeast, to the Colorado National Monument, just outside Grand Junction. Here, the Great Unconformity is, by the numbers, even greater. The time missing spans not 1.2 billion years, but 1.5 billion. The photographer frames a shot of the colorful, banded Chinle Formation—rock laid down some 220 million years ago, when the first dinosaurs were appearing in North America—sitting directly upon the 1.7-billion-year-old Precambrian basement. The story the image tells is of the dawn of the Age of Reptiles resting on the eroded nubs of a world that existed before complex life had even truly begun.

To capture these images is to ask a question: Where did the time go? The running hypothesis points to a global-scale scouring. One theory suggests the breakup of the supercontinent Rodinia initiated a continental, perhaps worldwide, outbreak of erosion. A competing idea is that the glaciers of a “Snowball Earth” ground the continents down to their foundations. In either case, the unconformity is the scar tissue from that planetary trauma. This great erasure, this grinding down of the old world, may have filled the oceans with the chemical building blocks—the phosphorus, the calcium, the iron—that fueled the Cambrian Explosion. The photographer, standing in a quiet canyon, framing a simple line between two different kinds of rock, is capturing the faint, distant echo of the moment the world nearly ended, and in so doing, cleared the stage for everything that was to come.

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