The New Trail of Time at Grand Canyon National Park - A Review

Continued...

The 2 km long timeline represents 2,000 million years of earth history with each million-year time segment marked at one-meter intervals with small brass rings embedded in the asphalt footpath. Such a layout means that one long stride represents one million years of time. At each 10-million year interval, a 4-inch diameter brass medallion displays the precise number of years shown along the trail. At the trails west end near the El Tovar Hotel is the 2,000 million year brass medallion, while a 0 million year medallion its located at the trails east end near the Yavapai Observation Station. Along its 2 km length visitors will find four beautiful stone portals, thirteen interpretive signs, and thirty-three concrete pedestals, with formation names and ages etched upon them, and topped with actual rock specimens from the canyon's inaccessible depths. Visitors now have a way to see and touch Grand Canyon rocks. The four portals are constructed at key junctures in the trail, are superbly rendered and are perhaps the exhibits' most stunning attraction. They are composed of actual rock specimens that have been proportionally measured, cut, polished, and placed within each 7-foot tall monument, presenting a quite recognizable vertical profile of the canyon. At their base, each portal contains the Precambrian crystalline rocks cut into a v-shape representing Grand Canyon's Inner Gorge. Slabs of layered Supergroup rocks are then placed at an angle on one side, all of which are covered with flat slabs of Paleozoic caprocks on top. The portals are both scientifically enlightening and wonderfully artistic, and many visitors already have been seen having their picture taken next to one of these scaled forms of the Grand Canyon. At each portal a semi-circular stone "patio" is laid with flat, time appropriate rocks that allow groups of people to admire the portals while standing off to the side of the trail.

The thirteen wayside signs focus on diverse topics such as the Great Unconformity, the ancient environments that created the rocks, and the canyon's carving in the last six million years. As visitors approach the east end of the trail, the wayside signs cover subjects covering recent climate change, Quaternary volcanism, and the relatively recent human history in Grand Canyon. In eight instances the wayside signs are complemented with viewing tubes placed adjacent to the signs and serve to direct the visitor's gaze towards key geologic features that can be seen in the canyon. These viewing tubes continue a long and time honored tradition at Grand Canyon National Park and in each instance a separate tube is provided for small children and taller adults. The viewing tubes help connect visitors with one of the more challenging aspects in the educational design of the trail – how to link a horizontal timeline with the vertical record of rocks that is to be seen in the canyon.

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ARTICLE AUTHOR:
Wayne Ranney, geologist, author, and river and trail guide

Flagstaff, AZ
wayneranney@earthlink.com

Author of:
Sedona Through Time, Ancient Landscapes and Carving Grand Canyon













Arizona Geology is published by the Arizona Geological Survey. | © The Arizona Geological Survey, 2011. All Rights Reserved.
Editor: Michael Conway