Geology of Bryce and Public Attraction Info.

The Geology of Bryce

and
Public Attraction Info

The geology of Bryce Canyon is a study rich with change and the exciting interaction between nature's forces. The creation of this curious landscape began approximately 60 million years ago, when much of northern Utah was groove by rivers and streams, and later by a system of lakes. These ancient drainage transported a variety of sediments, including sand, silt and clay, into basins where they settled to the bottom, forming soft, muddy beds.

Minerals were deposited along with the sediments of iron and manganese that would later oxidize to lend bright red, pink, yellow and violet hues to the rock, and calcium carbonate (CaCO3), which caused the eventual cementing of the sediment layers into an polluted form of limestone. Over time the waterways receded, leaving behind the multi-colored Claron Formation from which Bryce Canyon's remarkable scenery is carved. A scarcity of plant and animal fossils within these rock layers prevents scientists from learning much about the climatic conditions which existed in the area at the time these shaping events were taking place..

Beginning about 10 to 15 million years ago, a period of uplift began in the greater region of the southwest now known as the Colorado Plateau. This upward thrusting movement of the earth's surface eventually came to an end, but not before the great plateau had been elevated almost one vertical mile! Such tremendous force on the earth's curst led to a period of faulting, during which the western half of the Colorado Plateau was stretched and fractured to form a series of small plateaus.

The highest of these plateaus, the Aquarius, is visible to the east of Bryce Canyon. Bryce Canyon has been sheared from the eastern rim of the Paunsaugunt Plateau. The Paunsaugunt Fault separates the Paunsaugunt from the Aquarius Plateau and can be seen within the park boundary as one travels east on Highway 12. The striking pink and red hues of the Claron Formation contrasts noticeably with the subtle buff and gray of older rock layers.

Prior to the uplifting and fracturing of the Colorado Plateau, a river known today as the Paria flowed slowly across the featureless land. As the area began to rise, the Paria and its tributaries underwent a dramatic change in steepness, becoming fast-moving, and therefore, became a powerful erosive force. They cut their way easily through the weaker layers of the Claron, wearing back the eastern rim of the plateau, and carving the bowl-shaped amphitheaters of Bryce Canyon National Park.

Although low levels of rainfall today make the Paria River an intermittent force of nature, rain and snowmelt continue to flow down the plateau's sloping eastern escarpment, pushing back the rim of the plateau approximately one foot every 50 to 65 years. These rivulets, actually the headwaters of the Paria, carve pathways in the weak strata, eventually forming gullies and ridges known as "fins." Some layers of Claron are highly resistant to the intrusive forces of water. The harder layers of rock erode at a slower rate and serve as a "cap stone" to the soft, underlying layers. It is easy to see the way in which this geologic phenomenon has worked to sculpt many of the unusual shapes found at Bryce Canyon, commonly referred to as Hoodoos.

While the water's role shapes the spires and pinnacles of Bryce Canyon with an average annual rainfall of only 16 inches, the cold nighttime temperatures on the plateau further chisels the landscape with over 200 freeze-thaw cycles annually on south-facing slopes. During the relative warmth of day, snow and ice melt and trickle down into cracks in the rocks known as "joints." The formation of hoodoos has been, to a large extent, predetermined and hastened by these cracks. As temperatures fall below freezing, the water begins to solidify from the top down, expanding and exerting tremendous pressure, acting as a wedge to virtually pry rocks apart. Witness this powerful erosive force firsthand from the plateau rim on cold winter mornings, as the sound of falling rocks echoes through the canyons.

Even as new hoodoos are being carved from the plateau's rim, old ones are being washed away. The geological energy marches ever forward. The conditions and processes at work here are not unique, but the distinctive way in which all of the elements operate together results in the fantastic scenery that makes Bryce Canyon one of nature's spectacular wonders.

Back to Bryce Canyon