Regional Geology - Utah
Utah is the home of the upper levels of the Grand Staircase, the geologic steps that
begin at the base of the Grand Canyon in Arizona. The floor of the Grand Canyon is the
lowest point of the "Grand Staircase," a series of enormous geological "steps" that
climb up over the Kaibab Plateau into southern Utah, through Zion National Park, up
again through Bryce Canyon, before finally reaching the 11,311-foot summit of Brian Head
Mountain. As it rises up through successive layers of rock strata, the Grand Staircase
witnesses several billion years of geologic history. All through out this Grand
Staircase there have formed amazing works of wind and water erosion over billions of
years, giving us today a magical landscape unlike anything else on earth.
Utah Arches and Canyons
One of the best kept geologic secrets in the world are the fantastic canyons in Utah -
fantastic in that they come in shapes, sizes, and colors that are nothing less than
There are arches of sandstone creating bridges across the sky, windows worn through sand
stone buttes, towering spires, huge rocks balanced on tiny pedestals, multi-colored
canyons, and thousands of ancient petroglyphs carved in these canyon walls.
Combinations of salt left from when the area was under arctic seawater in the Mesozoic
Era (240 - 150 million years ago), water, ice, and minerals, all combine to make this
region one of the most amazing in topography and color. From the soft pink and brown
hues of Navajo Sandstone at Zion, to the rainbow of mineral colors at Bryce, to the
fiery red Entrada Sandstone at Arches, the natural canyon walls and nearly unbelievable
rock formations have left human visitors awe struck for thousands of years.
One step above the Grand Canyon in the Grand Staircase formation is Zion Canyon.
This canyon is a surround of warm pink and buff Navajo Sandstone and ranges in elevation
from 3,666 to 8,726 feet. Zion speaks of eons of time, some when lakes covered the
region and left layers of debris on their beds that became thousands of feet of deep
rock, and Zion also tells us of other times when their were hot dry winds blowing sand
dunes across the Southwest. Then 13 million years ago when the Colorado Plateau starting
lifting up, a river began to run through to form the canyon.
Today that river still runs, and is called the North Fork of the Virgin River.
The top step in the Grand Staircase is Bryce Canyon at elevations of 6,600 to 9,100 feet. Bryce Canyon National Park is not really a canyon at all, but is a series of fourteen amphitheaters that have been eroded out of the eastern rock face of the Paunsaugunt Plateau. The colored soils we see there are from the silt, sand, and limy skeletons of freshwater lake creatures deposited in 2,000 foot thick lake beds nearly 60 million years ago, soon after the dinosaurs ceased to walk the land. Around 13 million years ago, the lands were lifted, slowly, and split along fault lines. Water, snow and ice began to work away at the lakebeds once they were exposed to the air. This erosion carved the soft rock into spires, pinnacles, windows, arches and natural bridges. As much as the forms are astounding, the colors are also unexpected. Hematite gives the rocks their red and brown colors, limonite lends a surprising soft yellow, and manganese oxides provide a lavender blue.
Straddling the Colorado River and several large tributaries, Canyonland National Park is another sandstone marvel and contains a wonderful combination of ancient cliff dwellings, rock art, an the by far more ancient sandstone arches, teetering boulders on thin pedestals, and horizontally banded canyon walls. The area contains Navajo Sandstone 'slickrock' that are petrified sand dunes from the Jurassic Era, a geologic process that began when dinosaurs were dominating the land.
Rainbow Bridges and Natural Bridges National Monuments are two more remarkable geologic wonders in Utah. Science expeditions in the 1900s sough to determine which were the largest natural bridges in the world. Ultimately it was proven that Rainbow Bridge, named after a Navajo legend, was the largest natural bridge in the world spanning 275 feet. This bridge was formed as plate tectonics lifted the Colorado Plateau up a mile in the sky about 65 million years ago, increasing the pressure of small creeks into larger streaming forces, carving away at the sandstone as it traveled to a lower elevation to the southwest. Here, at the Rainbow Bridge, the softer Navajo sandstone was more easily carved away than the harder Kayenta sandstone that lay above it, and the result is a standing Kayenta sandstone bridge no longer supported by the soft Navajo sandstone it had once lain upon.
At Natural Bridges three impressive bridges span the canyons and were named in 1908 using Hopi words - Sipapu (place of emergence) being the largest, Kachina (spiritual guardians), next in size, and Owachomo (rock mound) the third in size. These bridges are made of cedar Mesa Sandstone and have ancient rock art carvings on them. Also carved by stream flows, these bridges were formed when debris from growing rivers actually punched through canyon walls that they had previously would around.
Further north in Utah, sits the masterpiece of sandstone bridge collections, Arches National Park. At Arches National Park there are more than 1,700 natural rock spans in that park alone. These gravity-defying wonders of natural rock took millions of years to create and area fragile protected wonder today. Their stone is primarily the fiery red of the Entrada sandstone, but there are the softer pink hues of the Navajo sandstone as well. No river runs through these arches as at Rainbow Bridge or Natural Bridges. Wind and ice instead carved these majestic arches.
Volcanoes found in Utah include :
· Santa Clara
· Bald Knoll
· Markagunt Plateau
· Black Rock Desert