The Canyon’s Clues to Earth’s History

Kaibab Limestone

250 million years old

This limestone has a creamy to grayish-white color. It was formed by a shallow sea rolling in and out many times. This layer is at the top of both rims. Fossils found here include sponges, corals, and brachiopods, or small sea animals.

Toroweap Formation

260 million years old

This slope is pale yellow to gray flaky limestone, sandstone, and shale. Reptile footprints are found here. They show that this zone was a desert when this was the surface.

Coconino Sandstone

280 million years old

These are huge cliffs of sandstone. This layer was left by wind, which blew sand across the area. Here you’ll find tracks of spiders, scorpions, and lizards.

Hermit Formation

285 million years old

The flaky shale gets its red color from iron oxide. That’s rust! This layer has fossils of reptiles and amphibian tracks. It also has fossils of insects, like a big dragonfly. The rock contains many worm burrows too. Fossils of conifers and ferns suggest that there may have been plenty of rain and maybe forests.

Supai Group

300 million years old

These layers are made of shale, limestone, and sandstone. They look like red stairs. They formed when amphibians were first evolving! Fossils here include corals and other small sea animals. Some places have fossils of land plants and reptile tracks.

Redwall Limestone

340 million years old

This steep limestone cliff forms a wall that is hard to cross. This layer separates the forest above it from the desert below. The area is stained red by iron oxides. They washed down from the layers above. This zone also has a lot of caves. Sea animal fossils are found here too.

Temple Butte Limestone

350 million years old

The western area has cliffs hundreds of feet high. This layer ranges in color from purple in the east to gray or cream in the west. Many sea fossils are found here.

Tonto Group

Group of layers 530 million years old

Muav Limestone (top left)
This layer is a gray limestone separated by shale and sandstone. There are few fossils here.

Bright Angel Shale (top center)
The shale is mostly green. It was created from mud left behind after water washed over the area. The rock contains sea animal fossils.

Tapeats Sandstone (top right)
This dark brown layer contains sea animal fossils.

Vishnu Complex

1 to 2 billion years old

The hard rocks at the bottom of the canyon are the oldest. They started as lava from erupting volcanoes. The melted rock cooled and hardened into many colors. You can see gray, black, blue, and even pink.