The Trail of Time is an interpretive walking trail that focuses on Grand Canyon's vistas and rocks, encouraging visitors to ponder, explore, and understand the magnitude of geologic time and the stories told by canyon's rock layers and landscapes. Walking the trail is intended to give park visitors a visceral appreciation for the magnitude of geologic time... .. This 4.56 km (2.83 mile) long trail is actually a geologic time-line. Each meter on the trail signifies one million years of Grand Canyon's geologic history; and bronze markers mark one meter intervals. Every tenth marker is labeled in millions of years. NPS Photo by Erin Whitakker .