We got an early start for the flight from Rawlins to Moab. We flew over several oil wells, and then the terrain began to rise again, offering very few options for a forced landing. We followed the Green River through the Dinosaur National Monument, which straddles the Colorado-Utah state line. The last photo shows a road in this park. It leads to the turn-around at Echo Park Overlook, Harpers Corner. It looks like it would be a pretty tough drive to get up there. It's 7625 feet above sea level.
If we had flown just fifteen minutes beyond Moab, we might have landed at this airstrip instead of driving to it. It's the Needles Outpost runway, next to Canyonlands National Park. The Outpost is a popular spot for fly-in lunches, and sometimes for campers. It's 4500 feet long, which is adequate but not overly long, almost 5000 feet above sea level on a hot day. We needed the car, anyway.
Although we were here to see two parks, even the drive into Moab offered
scenic delights. It runs through the Moab Fault, seen here from a viewpoint
in Arches National Park.
Caution: this photo is very wide (there's a smaller version here).
A dramatic break in the earth's surface occurred here about six million years
ago. Under intense pressure, unable to stretch, the crust cracked and
shifted. The highway parallels this fracture line.
After the rock layers shifted, the east wall of the canyon (from where the photo was taken) ended up more than 2600 feet lower than the west side.
We planned to visit two national parks while we were in Moab. First stop was the Needles in Canyonlands National Park. Newspaper Rock is on the access road into the Needles. The sign nearby tells us that it...
...is a petroglyph panel etched in sandstone that records approximately 2000
years of early man's activities. Prehistoric peoples, probably from the
Archaic, Basketmaker, Fremont and Pueblo cultures, etched on the rock from BC
time to AD 1300. In historic times, Utah and Navajo tribesmen, as well
as Anglos, left their contributions.
There are no known methods of dating rock art. In interpreting the figures on the rock, scholars are undecided as to their meaning or have yet to decipher them. In Navajo, the rock is called Tse' Hane' (rock that tells a story).
Unfortunately, we do not know if the figures represent story telling, doodling, hunting magic, clan symbols, ancient graffiti or something else. Without a true understanding of the petroglyphs, much is left for individual admiration and interpretation.
Leaving Newspaper Rock, we headed for the
Needles. This scene includes
Wooden Shoe Arch (third formation from the left), which we'll see closer in a
The Needles are a series of spires formed out of a red and white sandstone layer called Cedar Mesa Sandstone, which makes up most of the rock features in the Needles District of the Canyonlands Park. This 245 to 286 million year old layer was once a dune field on the eastern edge of a shallow sea that covered what is California, Nevada and western Utah today. Sand was blown in from this direction and formed the white bands in the Cedar Mesa Sandstone. The red bands came from sediment carried down by streams from a mountainous area near where Grand Junction Colorado, is today. These layers of sand were laid down on top of each other and created the distinctive rocks seen in the Needles District.
Starting about fifteen million years ago, the Colorado Plateau was pushed up thousands of feet. Rivers, such as the Colorado and the Green, cut down and carved deep canyons. Water, the primary force of erosion, eats away or weathers rock by attacking the cement holding the sand grains together. During storms, rushing water knocks loose sand and rocks as it flows down washes, causing additional erosion. The water naturally acts faster on areas of weakness within the rock, such as fractures and cracks. The Needles occur in an area with many fractures called joints.
The joints were formed in two different ways. The first was the Monument uplift, which begins around the Needles District and trends slightly southwest all the way to Monument Valley. This uplift caused brittle, surface rock like the Cedar Mesa Sandstone to crack as it was bent upward, forming a set of joints in a northeast-southwest direction.
A thick salt layer underneath the Needles district, known as the Paradox Formation, is the second cause of joint formation. The salt is flowing slowly toward the Colorado River and dragging the overlying layers with it. As the upper layers became stretched, they also fractured into joints. This action created a set of joints running northeast-southwest. In the Needles area, these two joint sets meet and form square blocks of rock between the joints. As water widened the joints, the squares were sculpted into pillars and spires that are today the Needles of Canyonlands.
In the very center of the first picture, there is a small cave in deep shadow, visible from the roadside. This is an Ancestral Puebloan granary tucked into a ledge above a dry wash, built 800 to 1000 years ago. Canyonlands National Park has dozens of similar structures, but few dwellings. This suggests that early inhabitants of the area farmed intensively, but lived here only seasonally.
Wooden Shoe Arch. We learned about how arches are formed and destroyed a day
after seeing this park, at
About 300 million years ago, this area was covered by an inland sea. As the water evaporated, it left behind a great salt basin into which many layers of sediment were deposited. Here, red sediments from the mountains to the East interfingered with white coastal deposits. These sediments were later transformed into the red and white sandstone of the Cedar Mesa formation that is the floor of the Needles District.
The buried salt, which flows under pressure and is dissolved by ground water, shifted under the sandstone, causing it to fracture. Weathering along the fractures carved Wooden Shoe Arch, and the other arches, spires, knobs, and fins that we see today.
Scenes from the auto road through the Needles District.
Pothole Trail offers dozens of examples. Potholes are naturally occurring basins or pools in sandstone that collect rainwater and wind-blown sediment. These potholes harbor organisms that are able to survive long periods of dehydration, and also serve as a breeding ground for many desert amphibians and insects. Potholes range from a few millimeters to a few meters in depth, and even the smallest potholes may harbor microscopic invertebrates. From an NPS web site,
To survive in a pothole, organisms must endure extreme fluctuations in several environmental factors. Surface temperatures vary from 140 degrees Fahrenheit in summer to below freezing in winter. As water evaporates, organisms must disperse to larger pools or tolerate dehydration and the drastic physical and chemical changes that accompany it.
The most extreme conditions exist when a pothole is dry. In addition to the wide temperature fluctuations, ultraviolet light from the sun can damage body tissues. Many aquatic organisms are adapted to acquiring oxygen through water and suffer when exposed to air. Pothole organisms have three main ways of dealing with drought.
"Drought escapers" are winged insects, amphibians and invertebrates that breed in potholes but cannot tolerate dehydration (e.g. mosquitoes, adult tadpole and fairy shrimp, spadefoot toads). In some cases, adults live in permanent water sources or on land and travel to temporary pools to mate and lay eggs. If the pool dries out before the young mature, they die. In the case of tadpole, fairy and clam shrimp, adults must lay their drought-tolerant eggs before the pool dries up.
"Drought resistors" (e.g. snails, mites) have a dormant stage resistant to drying out. These animals have a waterproof layer like a shell or exoskeleton that prevents body tissues from losing too much water while a pool is dry. By burrowing, these animals are able to seal themselves in the layers of fine mud that often coat the bottom of potholes and form an impermeable crust.
"Drought tolerators" (e.g. rotifers, tadpole and fairy shrimp eggs) are able to tolerate a loss of up to 92 percent of their total body water. This remarkable process, known as "cryptobiosis," is made even more remarkable by the fact that many cryptobiotic species can be rehydrated and become fully functional in as little as half an hour. Cryptobiosis is accomplished by a command center that remains hydrated while substituting sugar molecules for water throughout the rest of the body. This transfer maintains the structure and elasticity of an organism's cells during long periods of drought, and enables the organism to withstand the climatic extremes of the desert. In fact, brine shrimp have been hatched from cryptobiotic cysts that endured a flight on the outside of a spacecraft. Many tolerators have only one stage in their life cycle (e.g. egg, larva) that can survive desiccation, and will die if a pool dries up during another phase.
Pothole organisms not only have to endure dry spells, but also must evaluate conditions and decide when to break dormancy. Desert precipitation falls at irregular intervals, and once water enters a pothole there is no guarantee that there is enough for an organism to complete its life cycle. Most organisms living in potholes have very short life cycles, as brief as ten days, reducing the time water is required and allowing them to live in the shallow pools. Even vertebrates such as toads, which are found in other environments, display shorter development times when found in potholes.
However, the presence of water may not be the only cue used by eggs and dormant life forms to activate. Oxygen content, temperature, and other physical and chemical factors of the water may be evaluated. Some organisms produce different types of eggs that hatch on different cues; others lay eggs in different areas so that they experience slightly different environmental conditions. The net result is that not all eggs hatch at once and the species has a better chance of survival. After a pothole fills with water, the small ecosystem experiences many other changes. Water temperatures can be very high, while oxygen levels can be very low. As the pool shrinks from evaporation, its salinity increases and the pH changes. Many organisms are capable of surviving wide fluctuations in these factors, but for some these changes are an indication that the time for dormancy is near.
Some other scenes from the trail at Pothole Point.
Canyonlands National Park surrounds the confluence of the Green and Colorado Rivers. These rivers naturally divide the park into three sections. You can't get from one section to the other easily by car (no bridges), but you can see. This is a view of Islands in the Sky, generally considered to be the most accessible part of the park. These are buttes that haven't turned into needles yet. That will take a few thousand years or more.
It isn't possible to show the Needles in a normal photograph. This one is very wide (there's a smaller version here).
on to Arches