Stop 1: Rockhounding at the Dugway Geode Beds (June 8)
Geology of the Geode deposits:
Approximately 6 to 8 million years ago, volcanic activity occurred in western Utah and deposited an extrusive igneous rock called rhyolite. Trapped gasses formed cavities within the rhyolite, and millions of years of ground-water circulation allowed minerals to precipitate into the cavities. The result is geodes with spherical shapes and crystal-lined cavities.
Roughly 32,000 to 14,000 thousand years ago, a large body of water known as Lake Bonneville covered most of western Utah. The lake's wave activity eroded the geode-bearing rhyolite and redeposited the geodes several miles away in the Dugway geode bed area as lake sediments.
Most geodes are typically hollow whereas others are completely filled with massive, banded quartz. The most common mineral found within the geodes is quartz in various colors: clear (rock crystal), purple (amethyst), and pink (rose).
Photos from the area:
Stop 1.5: Arches of Arches National Park (Previous trip - April 2008)
Geology of Arches National Park:
The park lies atop an underground salt bed, which is responsible for the arches and spires, balanced rocks, sandstone fins and eroded monoliths. Thousands of feet thick in places, this salt bed was deposited across the Colorado Plateau some 300 million years ago when a sea flowed in the region and eventually evaporated. Over millions of years, the salt bed was covered with residue from floods and winds and the oceans that came and went at intervals. Much of this debris was compressed into rock.
The weight of the cover caused the salt bed below it to liquefy and thrust up layers of rock into salt domes. Whole sections dropped into the cavities. Faulting occurred and whole sections of rock subsided into the areas between the domes. The result of one such 2,500-foot displacement, the Moab Fault, is seen from the visitor center.
As this subsurface movement of salt shaped the landscape, erosion removed the younger rock layers from the surface. Except for isolated remnants, the major formations visible in the park today are the salmon-colored Entrada Sandstone, in which most of the arches form, and the buff-colored Navajo Sandstone. These are visible in layer cake fashion throughout most of the park. Over time, water seeped into the surface cracks, joints, and folds of these layers. Ice formed in the fissures, expanding and putting pressure on surrounding rock, breaking off bits and pieces. Winds later cleaned out the loose particles. A series of free-standing fins remained. Wind and water attacked these fins until, in some, the cementing material gave way and chunks of rock tumbled out. Many damaged fins collapsed. Others, with the right degree of hardness and balance, survived despite their missing sections. These became the famous arches.
Photos from Arches National Park:
Stop 2: Wild Rock Formations at Goblin Valley State Park and Famous Little Wild Horse Slot Canyon (June 9)
Geology of Goblin Valley:
The stone shapes of Goblin Valley result from millions of years of geologic history. The goblins are made of Entrada sandstone, which consist of debris eroded from former highlands and redeposited on a tidal flat (alternating layers of sandstone, siltstone, and shale). The goblins show evidence of being near an ancient sea. Joint or fracture patterns within the Entrada's sandstone beds create initial zones of weakness. The unweathered joints intersect to form sharp edges and corners with greater surface-area-to-volume ratio than the faces. As a result, the edges weather more quickly, producing spherical-shaped goblins.
Geology of Little Wild Horse Canyon:
Little Wild Horse Canyon is a popular slot canyon hike. A slot canyon is a narrow canyon, formed by the wear of water rushing through rock (sandstone in this case). A slot canyon is significantly deeper than it is wide. A majority of the 3-mile long Little Wild Horse Canyon measures about 3 ft across with walls over 100 ft from the top to the floor of the canyon. The striations and grooves on the canyon walls are evidence of the flow of water, which during flash floods is strong enough to sweep huge boulders through the canyon.
Photos from the area:
Stop 3: Pictographs and Petroglyphs of Horseshoe Canyon (June 10)
History of Horseshoe Canyon:
Horseshoe Canyon (originally Barrier Canyon) is a detached unit of Canyonlands National Park that was added in 1971. Its intriguing rock art is often considered to be the most significant in North America.
Horseshoe Canyon contains one of the finest displays of prehistoric Indian rock art in the United States. The famous Great Gallery, largest of several Horseshoe Canyon sites, is 200 feet long, 15 feet high, and contains dozens of fascinating red, brown, and white pictographs (pictographs are paintings on the rock) and a few petroglyphs (petroglyphs are carvings into the rock). The barrier canyon style paintings are at least 2,000 years old, and possibly as old as 8,000 years. The work was done by the Archaic People who lived in the area before the arrival of the Anasazi and Fremont Indian cultures. Archaeologists have struggled to interpret the strange figures that are depicted on the Great Gallery.
Photos from Horseshoe Canyon:
Stop 4: Drive through the Stunning Geologic Features of Capitol Reef National Park (June 10)
Geology and Native History of Capitol Reef National Park:
Capitol Reef encompasses the Waterpocket Fold, a warp in the earth's crust that is 65 million years old. In this fold, newer and older layers of earth folded over each other in an S-shape. This warp, probably caused by the same colliding continental plates that created the Rocky Mountains, has weathered and eroded over millennia to expose layers of rock and fossils. Erosion of the tilted rock layers continues today forming colorful cliffs, gleaming white domes domes, soaring spires, stark monoliths, twisting canyons, and graceful arches.
Fremont Indians lived near the perennial Fremont River in the northern part of the Capitol Reef Waterpocket Fold around 1000 CE. They irrigated crops of lentils, maize, and squash and stored their grain in stone granaries (in part made from the numerous black basalt boulders that litter the area). In the 13th century, all of the Native American cultures in this area underwent sudden change, likely due to a long drought. The Fremont settlements and fields were abandoned. Fremont rock art, such as that along HWY 12 running through the park, can be identified by the large trapezoidal figures often depicted wearing headdresses and ear baubles.
Photos from Capitol Reef National Park:
Stop 5: Colorful Hoodoos of Bryce Canyon National Park (June 11-12)
Geology of Bryce:
Bryce Canyon was not formed from erosion initiated from a central stream, meaning it technically is not a canyon. Instead headward erosion has excavated a series of large amphitheater-shaped features, cut into the hardened sediments that had previously been deposited on the Colorado Plateau. The largest amphitheater is Bryce Amphitheater, which is 12 miles long, 3 miles wide, and 800 feet deep.
The erosion has exposed delicate and colorful pinnacles (consisting of limestone, dolomite, and siltstone layers) called hoodoos that are up to 200 feet high. The hoodoos of Bryce Canyon are 60 million year old. The yearly weather cycle aids the process needed for a hoodoo to form. The freeze and thaw cycle loosens the slope surface, allowing debris to be sluffed off by water run-off. The material carried away works on the softer rock to create gullies, and ultimately canyons. The hard rock that was left behind is further eroded along its vertical cracks, again subjected to the freeze-thaw cycle carving the hoodoos.
Photos from Bryce:
Stop 6: Towering Sandstone Grandeur of Zion National Park (June 12-14)
Geology of Zion:
Over 200 million years ago the area where Zion National Park is today was a desert basin. Over vast amounts of time the mountains there eroded. The material was carried by slow moving streams and rivers and laid down in the vast basin, filling it with sand. Time passed and the sea covered the dunes as the environment changed. Calcium carbonate cemented loose grains of sand making hard sandstone. It turned the seabed to limestone and mud and clay to mudstone and shale, forming the sweeping diagonal cross-bedding that Zion National Park is famous for.
A gradual uplift of the Colorado Plateau caused the rivers to pick up speed and knife through the rock layers. Although some erosive forces, like flash floods, are dramatic, the subtle freezing and thawing of water seeping into cracks in the Navajo sandstone and ths slow action of roots are responsible for most of the changes that shape the canyon.
The soaring Navajo sandstone cliffs such as the Great White Throne and the Three Patriarchs were originally immense sand dunes. Slanting lines in the rock walls result form shifting winds as the sand dunes formed. Calcium carbonate is responsible for the white color of many of the rocks. The reddish rocks are also Navajo sandstone stained by iron oxides. Kayenta shale, which lies beneath the Navajo sandstone, is another main rock at Zion. The shale is much less permeable than the sandstone, so water runs along the surface of the shale and seeps out on the side of the nearest rock face, such as at Weeping Rock.
Photos from Zion:(hike up to Observation Point)
(hike up to Angel's Landing)
(at night in Springdale)
Stop 7: Mountain heights and limestone caves of Great Basin National Park (June 15-16)
Geology of Great Basin National Park:
Great Basin National Park lies about 10 miles off the Utah-Nevada border, on the Nevada side. It is within the Basin and Range physiographic province. The entire region has experienced thinning and deformation of the earth's crust, resulting in extensive faulting. Along these roughly north-south-trending faults, mountains uplifted and valleys down-dropped. This process, which continues today, produced the pattern of basin, range, basin, range that extends across the region.
At 13,063 ft, Wheeler Peak is the highest point in Great Basin National Park. It is also the second highest peak in Nevada. The rocks of Wheeler Peak first formed as layers of sand laid down at the sea's edge 600 million years ago. The layers cemented into sandstone, and heat and pressure turned the sandstone into quartzite. I hiked to the top of Wheeler Peak while I was in the park - the 60mph gusts on the ridge made the easy 4.3 mile trail hike a bit more like a climb!
Because of the over 6000 feet of elevation difference between the summit of Wheeler Peak and the surrounding Great Basin, the park hosts a range of zones - from sagebrush into forests of spruce and aspen, upward to terrain where bristlecone pines give way to rocky peaks. These pines are more than 3000 years old.
Another unique feature of the park is the limestone Lehman Caves. The formation of these caves began approximately 550 million years ago when thick deposits of limestone formed in a warm, shallow ocean. The limestone was eventually brought to the earth's surface by a series of geologic events, and also became fractured during these processes. Water seeped into the fractures. Carbon dioxide in the soil and air combined with the water to form carbonic acid, which was responsible for dissolving large rooms and cavities in the limestone, forming the large caverns of the Lehman Caves. The water table dropped and the water drained out of the underground chambers, but continued trickling of groundwater (containing dissolved limestone) has formed precipitates on the cavern walls, such as the beautiful stalactites, stalagmites, columns, draperies, flowstone, helictites, popcorn, and rare shield formations.
Photos from Great Basin National Park:(Driving across the Utah-Nevada border)
(Wheeler Peak area)
Climbing detour on the way home: Palisade Traverse (June 19-21)
As no trip can be complete without climbing, on the way home I detoured to the Californian Sierras to meet up with my friend Mark to do the classic Palisade Traverse. Although we didn't climb to as many of the summits as we had planned, it was nevertheless a fun adventure. Click the link for the trip report.
Drive home: Unique and scenic landmarks (June 22-25)
My drive home to Seattle took me by several unique and scenic landmarks, such as Yosemite, In N' Outs, Mt. Shasta, Crater Lake, derelict gas stations, and the Oregon coast, among others. Some of my favorite photos from the drive home are below.
Photos from the drive home:
Another climbing detour on the way home: Mount St. Helens (June 26)
The Mount St. Helens Eruption:
Mount St. Helens is most famous for its catastrophic eruption on May 18, 1980, which was the deadliest and most economically destructive volcanic event in the history of the US. Fifty-seven people were killed; 250 homes, 47 bridges, 15 miles of railways, and 185 miles of highway were destroyed. The eruption caused a massive debris avalanche, reducing the elevation of the mountain's summit from 9,677 ft to 8,365 ft and replacing it with a 1 mile wide horseshoe-shaped crater. The debris avalanche was up to 0.7 cubic miles in volume.
Trip report for my climb:
I should have known that when I stopped to see Mount St. Helens, I wouldn't make it home to Seattle that night. I wanted to climb it. Anyway, climbing the volcano would allow me to get a closer look over the rim at the gaping crater. Click the link below for the trip report.