Plate Tectonics and the Rock Layers of Grand ... - Gsenmschool.org

Grand Staircase-Escalante National Monument Geology Unit 2
Student Activity
Geologic Formations of GSENM
Studying the geology of Grand Staircase-Escalante National Monument is like reading a
history book of the Mesozoic Era, its ancient environments, plants, and animals. Though the
Monument’s rock layers are predominantly from the Mesozoic, there are layers on top and
bottom that formed in the Cenozoic and Paleozoic Eras, respectively. Altogether, the rock
layers of the Monument reveal sediments and fossils deposited over 270 million years of
geologic time.
The following information will focus on the “Grand Staircase,” a series of five colorful cliffs
rising from south to north, gaining over 5,000 feet of elevation.
Pink Cliffs
Gray Cliffs
White Cliffs
Vermilion Cliffs
Chocolate Cliffs
The Grand Staircase from LeFevre Overlook, North Kaibab Forest
Most formations are composed of several “members,” each having a unique time span, geology,
and environmental history. The geologic information on these pages has been simplified and
covers only the formations, not their members.
Many of the rock formations are NOT equally distributed throughout the Monument. A
prominent layer in the west may be absent in the east, or it may be replaced by another
formation of the same geologic age. These variations are noted in text and labeled “East” or
“West” on the following pages.
There are missing chapters in the story of the Grand Staircase. These missing chapters, or
missing rock layers, are called unconformities. Unconformities are areas where the rock for a
particular age is no longer present in the local sequence of strata. Unconformities are included in
3