It should also come as no surprise that Zion National Park, where Navajo Sandstone attains its maximum exposed thickness of 2,300 feet, has the deepest, narrowest canyons on the Plateau. As thick as this Navajo layer is, several major streams in Zion have sliced all the way down through it to encounter the river-deposited Kayenta Formation below. As soon as the streams hit this Kayenta layer, the canyons begin to grow wider because the Kayenta crumbles away and causes the overlying solid blocks of Navajo to collapse into the canyons, thus widening them. This is precisely why Zion Canyon grows progressively narrower as you drive upcanyon. The next time you park your car at the end of the road, look at the canyon walls at river level, and you'll see the Kayenta layer just starting to show.
Field Guide Suggestions
As part of my workshops in southern Utah, I always include a brief discussion of the geologic history of the place we're photographing and, as a reference, I carry a copy of Ancient Landscapes of the Colorado Plateau by Ron Blakey and Wayne Ranney, with its beautiful full-color diagrams. In addition to this book, I also recommend The Geology of the Parks, Monuments, and Wildlands of Southern Utah by Robert Fillmore.
Knowing how to identify this Kayenta layer has played a critical role in my photography. I soon discovered that wherever this layer is exposed along the floors of canyons with small streams, the water flowing across its surface produces beautiful sculpted pools and waterfalls such as in "The Subway" in Zion or the sensuous stream-carved formations along Coyote Gulch in the Escalante Canyons. If you explore canyons floored with Navajo Sandstone and follow the streams to the locations where they eventually cut all the way through the Navajo into the Kayenta—voilà—waterfalls! The Escalante region is replete with canyons like this.
Once you learn the basic geology of this remarkable landscape, not only will you come to appreciate the region more, but your photography will benefit as well.
You can see more of James Kay's photographs and sign up for his workshops at www.jameskay.com.