The Grand CanyonTells the Story of North America

Knowing how and where rocks are formed allows us to read the story written in the rocks.

A mile thickness of rocks of the Great Plains are exposed by uplift and erosion by the Colorado River.

Rocks of the Rocks of the Grand CanyonGrand Canyon

Separate the larger puzzle into a series of smaller puzzles (I.e., each group of rocks) Metamorphic rocks (oldest) Intrusive igneous rocks Sedimentary rocks lying on an

irregular metamorphic surface Sedimentary layering Erosion of the canyon (Youngest event)

Rocks of the Rocks of the Grand CanyonGrand Canyon

Each group of rocks is separated by a gap in the geologic record (formations and contacts) Metamorphic rocks Metamorphism Granite Intrusion of silicic magma Eroded surface Uplift and erosion Sedimentary rocks Shallow inland seas Erosion of the Canyon Recent uplift

Metamorphic and Igneous Rocks

Metamorphism of sedimentary rocks

Igneous intrusion during later stages of metamorphism (during mountain building)

Uplift and erosion (during and after mountain building)

(nonconformity)

Sedimentary Rocks

Deposition of sediments on eroded metamorphic and igneous rocks.

Uplift and erosion exposing sedimentary layers and

Eventually expose Igneous and metamorphic rocks again

G Uplift and Renewed Erosion

Erosion and Exposure

Uplift and erosion exposing sedimentary layers and

Eventually Igneous and metamorphic rocks again

G Uplift and Renewed Erosion

G Uplift and Renewed Erosion

Formation of the

Grand Canyon

450Million Years Old

380

350Sandstone

Shale

Limestone

300million years ago

Formation of the

Grand Canyon

Regional UpliftTilting (or folding)

450

380

350Sandstone

Shale

Limestone

Erosion

280million years ago

1. Regional Uplift, Tilting (or folding), Erosion

Formation of the

Grand Canyon

450

380

350Sandstone

Shale

Limestone

Regional Uplift

Erosion

270million years ago

1. Regional Uplift, Tilting (or folding), Erosion

Formation of the

Grand Canyon

450

380

350Sandstone

Shale

Limestone

Regional Uplift

Erosion

260million years ago

1. Regional Uplift, Tilting (or folding), Erosion

Formation of the

Grand Canyon

450

380

350Sandstone

Shale

Limestone

Regional Uplift

Erosion

250million years ago

1. Regional Uplift, Tilting (or folding), Erosion

Formation of the

Grand Canyon

240million years ago

1. Regional Uplift, Tilting, or folding) causes Erosion

2. Erosion surface indicates gap in geologic record

450

380

350Sandstone

ShaleLimestone Gneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Sedimentation (e.g., clay)

220million years ago

1. Regional Uplift, Tilting (or folding), Erosion

2. Erosion surface, gap in geologic record

3. Continuous Sedimentation

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Sedimentation (e.g., lime mud)

Shale (220)

210million years ago

1. Regional Uplift, Tilting (or folding), Erosion

2. Erosion surface, gap in geologic record

3. Continuous Sedimentation

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Sedimentation (e.g., quartz sand)

Limestone(210)

200million years ago

Shale (220)

1. Regional Uplift, Tilting (or folding), Erosion

2. Erosion surface, gap in geologic record

3. Continuous Sedimentation

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Sedimentation (e.g., immature sand)

Shale (220)

Limestone(210)

Quartz Sandstone(200)

190million years ago

1. Regional Uplift, Tilting (or folding), Erosion

2. Erosion surface, gap in geologic record

3. Continuous Sedimentation

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Shale (220)

Limestone(210)

Quartz Sandstone(200)

180million years ago

Arkose (190)

1. Regional Uplift, Tilting (or folding), Erosion

2. Erosion surface, gap in geologic record

3. Continuous Sedimentation

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Arkose (190)

Shale (220)

Limestone(210)

Quartz Sandstone(200)

170million years ago

1. Regional Uplift, Tilting (or folding), Erosion

2. Erosion surface, gap in geologic record

3. Continuous Sedimentation

4. Sedimentation ceases

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

ErosionArkose (190)

Shale (220)

Limestone(210)

Quartz Sandstone(200)

160million years ago

1. Erosion of horizontal beds

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Shale (220)

Limestone(210)

Arkose (190)

Quartz Sandstone(200)

150million years ago

1. Erosion of horizontal beds2. Loss of geologic record

(i.e., Arkose)3. Formation of a horizontal

erosion surface

Erosion

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Shale (220)

Limestone(210)

Arkose (190)

Quartz Sandstone(200) Sedimentation (e.g., reef)

140million years ago

1. Erosion of horizontal beds2. Loss of geologic record

(i.e., Arkose)3. Formation of a horizontal

erosion surface4. Renewed Sedimentation

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

Shale (220)

Limestone(210)

Arkose (190)

Quartz Sandstone(200)

130million years ago

1. Erosion of horizontal beds2. Loss of geologic record

(i.e., Arkose)3. Formation of a horizontal

erosion surface4. Renewed Sedimentation

Limestone (140)

450

380

350Sandstone

Shale

LimestoneGneiss (1,500) Granite (280)

Gabbro (790)

Formation of the

Grand Canyon

450

380

350Sandstone

Shale

Limestone

Shale (220)

Limestone(210)

Arkose (190)

Quartz Sandstone(200)

120million years ago

1. Erosion of horizontal beds2. Loss of geologic record

(i.e., Arkose)3. Formation of a horizontal

erosion surface4. Renewed Sedimentation

Limestone (140)

Gneiss (1,500) Granite (290)

Gabbro (790)

Formation of the

Grand Canyon

Deciphering Relative Ages Principles give

sequences of geologic events

Unconformities indicate gaps in the geologic record

Shale

Limestone

Quartz Sandstone

Limestone

Sandstone

Shale

LimestoneGneiss Granite

Disconformity

Angular Unconformity

NonconformitiesGabbro

Uplift and Erosion

As the land is lifted up by tectonic forces

A stream will attempt to maintain its base level by

Cutting down into the rocks due to accelerated erosion

The Grand Staircase

Eastern Zion National Park