The Grand Canyon
By Ryan Arthur and Kole
Patton
Brief Overview
• Throughout this chapter we will learn how
to interpret the rock record of the Grand
Canyon.
• We will learn how to explain how fossils
can reveal the geologic history of the GC.
Vocab
• Outcrop- An exposed rock layer of any type.
• Vishnu SCHIST- Oldest rock in the GC.
• Tapeats Sandstone, Bright Angle Shale, Muav
Limestone- All deposited during the Cambrian Period.
• Redwall Limestone-This rock represented the
Mississippian Period.
• Supai Formation- Was deposited during the
Pennsylvanian Period
• Hermit Shale, Coconino Sandstone, Toroweap
Formation, and Kaibab Limestone- Represented the
Permian Period.
History In Rocks
• Geologists can determine parts of the Earth’s history by observing the outcrops of the canyon
walls.
• They can do this by following the law of Superposition.
• The geologists have found that the older the rocks, the farther down the cliff wall they will be. The
younger the rocks, the further up the cliff wall they will be…..(NO SCHIST)
• The bottom and the oldest rock in the canyon is Vishnu Schist.
• Tapeats Sandstone, Bright Angel Shale, Muav Limestone were all deposited during the Cambrian
Period and make up the lover walls of the GC.
• Geologists believe that many of the periods between the Cambrian and the Mississippian Periods
were eroded and worn away.
• They think that the Ordovician, Silurian, and Devonian periods were times of uplift and of great
erosion in the canyon.
• The Mississippian Period was represented by Redwall Limestone. Redwall Limestone when the
GC region was submerged under a shallow sea.
• The Supai Formation was deposited during the Pennsylvanian Period.
• The Permian Period was represented by the Hermit Shale, Coconino Sandstone, the Toroweap
Formation, and the Kaibab Limestone.
• The Rocks labeled above make up the upper layers, or the newest rocks of the canyon.
• Kaibab Limestone is currently the very newest and the top of the Colorado Plateau.
• The Colorado Plateau is a part of the Grande Canyon……(you don’t have to write this bullet)
• All of the Schist above reveals more about the geologic history of the GC region.
History in Fossils
• Through radioactive dating geologists have estimated the age of the fossils
found in the many rock layers of the Grand Canyon.
• The fossils are evidence of the kind of life that existed in those regions
during the various periods.
• Limestone and Shale often contain fossils of marine organisms such as
clams, fishes, and corals.
• The Bright Angle Shale contains many Trilobites, Marine Invertebrates, and
Brachiopods.
• The fossils show that a distinctive group of animals lived during each period
represented by the rock layers.
• Paleontologists can trace the changes in many of the organisms by
examining the remains found in successive rock layers.
• Analysis of the fossils found in older and lower rock layers through the
younger, upper layers suggests a sequence of events.
• These fossils indicate that early simple life forms gradually became either
extinct or changed into more complex forms.
• The position, composition, and fossil content of the rocks in the GC.
The End
• This Project is made by Kole Patton and
Ryan Arthur thanks to Ms .Gregory for
giving us a good grade……………………
Please ^_^