Its the Fault of Bright Angel
A
cache
by geodarts
Hidden
:
10/23/2009
Difficulty:
Terrain:
Size: 
(Not chosen)
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From the Visitor's Center at the North Rim, walk the trail to Bright Angel Point, with spectacular views of the Canyon and its geological history.
The listed coordinates take you near the start of the trail to Bright Angel Point. As you walk the short .25 mile trail, you may see fossils imbedded into the Kaibab limestone; hear the sound of water at Roaring Springs Canyon to your left; or notice the transition from the forests of the plateau to the pinyon and juniper on the canyon slopes as plants adapt to the changing conditions of the geology found here.
Midway along the trail, look to the right, across the Transept Canyon. A 1991 landslide of Coconino Sandstone cascaded into the Canyon, trailing debris across the walls. The slide shows that the erosional process that formed the area is still at work.
When you reach the end of the trail, look out to the South Rim, 10 miles away. The uplift that occurred here placed the North Rim around 1000 feet higher than the other side of the Canyon.
The depths of the canyon record events that stretch our understanding over a period of nearly two billion years, almost halfway back in the earth's history. The walls of the canyon are much more than layers of rock, then, but show the rise and fall of oceans and continents.
Though invisible at Bright Angel Point, the Colorado River is the erosive force responsible for the depth of Grand Canyon. Each kind of rock within the canyon erodes in its own manner. Shales erode to slopes. Harder sandstones and limestones tend to form cliffs. The extremely hard metamorphic rocks at the bottom of the canyon produce the steep-walled inner gorge.
Over the past 5-6 million years, the river has carved a canyon one mile deep. However, it does not act alone. Erosion from other sources: freezing and thawing, heating and cooling, storms that have battered the North Rim, all play a role in forming what you see from the Point.
These forces include the faults that can be seen cutting through almost every geologic layer of the Canyon. Faults are fractures in the earth along which movement occurs. In particular, the Bright Angel Fault stretches across the Grand Canyon from the south through Bright Angel Canyon, which was formed through erosion along the fault, until it terminates near the North Rim. The Bright Angel Fault is still active and has produced small earthquakes that visitors sometimes feel. You will learn more about this Fault at Bright Angel Point itself.
Logging Requirements
Email the owner with the name of this cache and answer the following questions:
- Look at the Transept Canyon landslide on your way to the Point. Briefly describe the slide area (you can note the color, estimate the size, or describe any other thing that you notice about it).
- Read the geological information on the interpretive sign at the Point. Describe how the Coconino Sandstone was displaced across the canyon and how many feet it moved.
- Include the name of one other fault that is identified at Bright Angel Point.
- As the action of the faults and effect of erosion continue, what kinds of changes, if any, do you think might occur at this Point?
Pictures are not required under the current earthcache guidelines. However, photos of your favorite geological formation or the fossils that can be seen on this trail are a welcome addition to your online log.
Park Information
When visiting this earthcache, please stay on the designated trails and take care to leave nothing behind.
The walk to Bright Angel Point is short. but be sure to bring water when the weather is hot and take care in storms.
The North Rim Visitor Center, as well as lodging and camping within the park, is open from mid-May through mid-October. Roads are closed during the winter due to snow. The National Park Service can assist you in planning your visit.
For More Information
The National Parks Service has an excellent brochure of the Bright Angel Trail that will help guide your way along it.
The Park also provides an overview of the Canyon's Geological Formations as well as Geologic Views that will enrich your understanding and visit to the area. You can also learn more about the North Rim Geology from Anabelle Foos of the University of Akron.
Additional Hints
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