Why learn about Sedimentary Rocks

• Source of building materials

• Source of fossil fuels (oil,coal,etc)

• Fresh water source

• Evidence of past surface conditions

• Fossils

Sedimentary Rock:

Clastic - particles deposited, cemented – like sandstone, shale

Chemical - precipitation out of solution – like salt, gypsum, some limestone

Organic - accumulation of parts of plants and animals - swamps (coal), shells (limestone)

Sandstone

Conglomerate

Breccia

Coquina (kō-KĒ-na)

Chemical Sediments

Sedimentary Structures

Graded bedding

Kaibab Limestone - 250 million years old, forms the surface of the Colorado Plateaus.

Toroweap Formation - 255 million years old, mostly limestone.

Coconino Sandstone - 260 million years old, pure quartz sand, petrified sand dunes.

Hermit Shale - 265 million years old, soft, easily eroded shales

Supai Formation - 285 million years old, shale intermixed w/ limestone and sandstone. Fossilized muddy river delta that fed into an ancient sea.

Unconformity

Redwall Limestone - 335 million years old ocean limestones.

Temple Butte Limestone - 350 million years old, freshwater limestone.

Unconformity

Muav Limestone - 515 million years old, limestone that is separated by beds of sandstone and shale.

Bright Angel Shale - 530 million years old, mudstone shale with thin layers of sandstone and sandy limestone.

Tapeats Sandstone - 545 million years old; Ripple marks suggest formation in shallow seas.

Great Unconformity – almost 300 m.y. gap!

Chuar Group - 825 to 1,000 million years old, mixture of sandstone, limestone and shale.

Nankoweap Formation - 1,050 million years old, coarse-grained sandstone.

Unkar Group - 1,100 to 1,250 million years old, contains lava flows & sedimentary rx

Unconformity – Gap from 1.25 to 1.7 b.y.

Vishnu Schist and Zoroaster Granite - 1,700 to 2,000 million years old. The Vishnu schist – used to be sandstone, limestone, and shale

This Vishnu Schist and Zoroaster Granite roots of an ancient mountain range, taller than Rockies.

Playa (“dry” basin salt flat)

Salt mine:

Bonneville Salt Flats:

Q. Why is St. Louis covered with limestone and other ocean-formed sedimentary rocks?

A. Many reasons (need to talk about climate, plate tectonics, continental development)