The Grand Canyon as a History Book: Rock Layers Reveal Earth’s Past

The Grand Canyon’s exposed strata read like chapters of a geologic history book. Each layer records a distinct era:

• Vishnu Schist (1.7 Ga): Metamorphic basement—Earth’s early crust.
• Grand Canyon Supergroup (1.2–0.54 Ga): Sedimentary record of shifting climates and seas.
• Tapeats Sandstone (545 Ma): First fossil‑bearing layer—trilobites, brachiopods, worms.
• Kaibab Limestone (270 Ma): Youngest layer—Permian marine fossils (corals, brachiopods, clams).

The Colorado River’s incision through these layers reveals nearly two billion years of planetary history, making the canyon a natural laboratory for geologists and a awe‑inspiring timeline for visitors.