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


Another fascinating feature of the TOT is the way time itself is metrically expanded for the last one million years. Near its eastern terminus, the "Million Year Trail" moves visitors through a series of changing time-to-distance scales, helping them to shift their thinking from the thousands and hundreds of millions of years they have been seeing to a more human centered time perspective - millennia, centuries, decades, and finally individual years. The "Million Year Trail" begins with an inset brass line that runs diagonally across the trail to highlight the change in scale. Meter-spaced medallions are then labeled for each 100,000 years - 900,000 years, 800,000 years, and so on. At the medallion labeled 200,000 years, time is scaled down once again to 10,000-year intervals - 190,000 years, 180,000 years, etc. Each interval is still one meter in length but time is continually "stretched" a few times in this way along the trail. The last 60 meters have a medallion for each year – 60 years, 59 years, 58 years, etc.

Brass medallion marking the 1600 Million Year point on the Trail of Time.

I love the TOT and found only a few things I might have done differently. A certain Proterozoic bias is apparent in some of the rock units chosen for display. Volumetrically limited members of some Supergroup units share equal visual representation as the more widespread and easily observed Paleozoic rock formations. And along a one-quarter length of the trail that has no signage at all, I might have added one additional sign between the 1,400 and 1,200 million-year medallion telling people that the Vishnu highlands were being leveled by erosion at this time. Perhaps in this way the exhibit could help show visitors how geologic reasoning works to interpret those times where no rock record exists. Lastly, I wish there would have been medallions for individual years up to 100 years instead of only 60 years. Practically everyone then who walked the trail could stand on "their year."

The trail's originators seem keen to adapt some aspects of the exhibit's design as ongoing evaluations warrant it. And any minor quibbles quickly fade away in light of the exhibits' overall necessity and desirability at Grand Canyon National Park. Our science is becoming increasingly relevant to a society that scratches every hidden corner of the planet for energy resources while at the same time (ironically) strives to understand climate change. As geologists, we can and should be major contributors in policy discussions and decisions. But regrettably, we as a community until very recently have been so bound up in our endless enthusiasm for "all things earth" that we have forgotten the masses of citizens who so far have shown little interest in or knowledge about what we do or how the geo-system works. This exhibit is a welcome, innovative, and needed addition in addressing these shortcomings. And for those of us who love to share the deeper meanings that the Grand Canyon can provide, the Trail of Time is a powerful tool that can direct ordinary people's thinking towards things geologic. This is only right and natural at a place like Grand Canyon - a place that changes lives everyday. This exhibit will facilitate that change for untold numbers of future visitors and many of them just might get turned on to geology without a geologist in sight!

The Trail of Time was conceived, designed, and installed by Karl Karlstrom, Laura Crossey, Michael Williams, Steven Semken, Judy Hellmich-Bryan, and Ryan Crow. Financial support came from the National Science Foundation and all work and support was provided by Grand Canyon National Park. You can learn more about the trail at: and Journal of Geoscience Education, v. 56, n. 4, Sept., 2008 p. 354-361.

Suggested reading:
Journal of Geoscience Education, v. 56, n. 4, Sept., 2008 p. 354-361

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Wayne Ranney, geologist, author, and river and trail guide

Flagstaff, AZ

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