Paleo Slide Set: Packrat Middens: Vegetation & Climate Variability in the Southwestern United States
Aerial view of the eastern Grand Canyon.

One of the more interesting regions for packrat midden research has been the Grand Canyon. 
Almost 350 km long, up to 30 km across, and more than 1600 m deep, the Grand Canyon is the 
world's most intricate network of gorges, canyons, and ravines. In its spectacular walls of 
colorful stone, the Grand Canyon records nearly 1.5 billion years of the earth's history. 
As the Colorado Plateau pushed upwards during the Pliocene and Pleistocene Epochs, the 
Colorado River entrenched itself through layer after layer of geologic history. The exposed 
cliffs harbor numerous caves and rock crevices inhabited by packrats, which have left a spectacular 
vegetation record of what some Quaternary geologists call radiocarbon time, or the last 40,000 years. 

Photo Credits:
Kenneth L. Cole 
U. S. Geological Survey & NOAA National Geophysical Data Center