Bryce Canyon Geology

The Grand Staircase:

The Grand Staircase is an immense sequence of sedimentary rock layers that stretch south from Bryce Canyon National Park through Zion National Park and into the Grand Canyon. In the 1870s, geologist Clarence Dutton first conceptualized this region as a huge stairway ascending out of the bottom of the Grand Canyon northward with the cliff edge of each layer forming giant steps. Dutton divided this layer cake of Earth history into five steps that he colorfully named Pink Cliffs, Grey Cliffs, White Cliffs, Vermilion Cliffs, and Chocolate Cliffs. Since then, modern geologists have further divided Dutton's steps into individual rock formations.

What makes the Grand Staircase worldly unique is that it preserves more earth history than any other place on earth. Geologists often liken the study of sedimentary rock layers to reading a history book--layer by layer, detailed chapter by detailed chapter. The problem is that in most places in the world, the book has been severely damaged by the rise and fall of mountains, the scouring of glaciers, etc. Usually these chapters are completely disarticulated from each other and often whole pages are just missing. Yet, the Grand Staircase and the lower cliffs that comprise the Grand Canyon remain largely intact speaking to over six hundred million years of continuous earth history with only a few paragraphs missing here and there.

Unfortunately, the Grand Staircase is such a vast region of rock that no matter where you stand on its expanse, most of it will be hidden behind the curvature of earth. Places such as Yovimpa Point and the north slope of the Kaibab Plateau are the exception where even a non-geologist can discern the individual chapters of this colossal history book--these immense steps of Dutton's Grand Staircase.

Windows or arches are natural holes that form along cracks and weak spots in thin walls of rock called "fins." By convention these holes must be at least three feet in diameter in two perpendicular directions to earn the name arch or window. An imprecise distinction is often made between bridges and arches in terms of the processes that form them. It's important to remember that gravity is the key factor in either case. Nevertheless, the distinction is that bridges are carved by flowing water, whereas arches can be carved by everything else except flowing water. Indeed, in very few circumstances is it possible to say that flowing water had zero contribution in the development of one of these natural holes. Therefore, geologists often prefer the term window to collectively describe any large hole in a rock. At Bryce Canyon National Park,most of our windows are carved by frost wedging.

Hoodoos are tall skinny spires of rock that protrude from the bottom of arid basins and "broken" lands. Hoodoos are most commonly found in the High Plateaus region of the Colorado Plateau and in the Badlands regions of the Northern Great Plains. While hoodoos are scattered throughout these areas, nowhere in the world are they as abundant as in the northern section of Bryce Canyon National Park. In common usage, the difference between Hoodoos and pinnacles or spires is that hoodoos have a variable thickness often described as having a "totem pole-shaped body." A spire, on the other hand, has a smoother profile or uniform thickness that tapers from the ground upward.

Walls and Narrows:
Walls or fins are narrow walls of rock, bound by joints or fractures on either side. As weathering and erosion open the cracks wider and wider they form narrows or slot canyons. The wall left standing in between two slot canyons is called a fin. As fins develop, differential erosion accentuates different rock hardness leaving them with a rugose appearance.

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