Geology

GRAND CANYON NATIONAL PARK

The Grand Canyon is a geologic masterpiece whose towering walls of layered rock reveal the region’s history in a way only geology can.  It’s a story of the region’s sedimentary deposits, volcanism and river erosion. Geologists have identified almost 40 rock layers within the Grand Canyon’s impressive 277-mile length and many mysteries remain.

The snaking Colorado River slowly sculpted the Grand Canyon into Colorado Plateau Province and its four plateaus. The Canyon’s stratified walls reveal two billion years of geologic forces. Meanwhile, granite gorges remain as evidence of metamorphosed magma almost two million years ago. Many of the Grand Canyon’s cross sections also tell of sedimentary deposits from marine and coastal shifts as well as volcanic activity.

The appearance of the Grand Canyon as we know it today was largely formed throughout the late Cenozoic Era during which erosion from the Colorado River carved out the Canyon.

 

 

YELLOWSTONE NATIONAL PARK

Various geological forces have created, and continue to create, the Greater Yellowstone ecosystem and landscape. It’s a dynamic, active combination of incredible natural forces.

Yellowstone remains one of the earth’s most geologically volatile regions, and greater Yellowstone sports more than 10,000 hydrothermal features—500 of which are geysers. This high concentration of active geysers makes Yellowstone home to half the world’s total geysers and the world’s largest concentration.

Yellowstone is also home to the world’s largest known volcanic eruptions, one of which created the world’s largest known calderas. Petrified trees created by andesitic volcanic eruptions around 50 million years ago dot the Yellowstone landscape.

 

Yellowstone’s Hydrothermal Wonders

Yellowstone’s hydrothermal activity is definitely eye catching as well as one of the primary reasons Yellowstone became the first national park. Along with Yellowstone’s 10,000 hydrothermal features, the park also boasts of steam vents, hot springs, and mudpots.

The park’s extensive hydrothermal system serves as a visible expression of the Yellowstone volcano whose submerged, partly molten system of magma, releases incredible heat. The hydrothermal system also depends upon Yellowstone’s water sources, such as the rain and snow that seep down from mountains surrounding the Yellowstone Plateau. These geologic factors merge to create Yellowstone’s internal plumbing.

 

Where to See Glacier Evidence in Yellowstone:

  • Lamar Valley: Moraine and large deposited boulders and ponds between Yellowstone and Lamar rivers are remains from glacial landslides.
  • Hayden Valley: Hayden Valley remains littered with glacial remains left after the most recent glacial recession. The valley’s marshy landscape is due to the glacial till, clay, and lake sediments from the glacial activity.
  • Upper Geyser Basin: Volcanic rocks and deposits can be found here and store water required for geyser activity.
  • Mammoth Hot Springs: Thermal kames exist here. Ice had formerly topped Bunsen Peak and Mount Everts.
  • Swan Lake Flat: The wetlands and meadows of Swan Lake Flat were formed from glacial retreat, along with the northwestern Electric Peak.
  • Madison Valley: Remnants of glacial moraines and outwash can be found here.
  • Fountain Flats: Twin Buttes and Porcupine Hills are thermal kames.
  • Tower Fall Area: Sedimentary remains from Yellowstone’s oldest known glacier may be found here. Further, erratics (large boulders) evidence Yellowstone’s most recent major glaciation.

 

 

BRYCE CANYON NATIONAL PARK

Though Bryce Canyon lays claim to the term “canyon,” this designation is technically incorrect as Bryce Canyon was not formed by flowing water. Rather, Bryce Canyon’s stunning geologic formations have been formed from frost wedging and the acidity of rain water.

 

HOODOOS

Hoodoos en masse puncture Bryce Canyon’s northern region. These “totem-pole” shaped rock spires can be as tall as a human over top a 10-story building. Hoodoos are formed from two weathering processes—frost wedging and rain—and their erosion processes effects the softer and harder rock layers.

Bryce Amphitheater, Navajo Loop Trail, or Queen’s Garden Trail are some of the most popular places in Bryce Canyon National Park to see hoodoos.

 

THE GRAND STAIRCASE

The Grand Staircase, the immense chain of sedimentary rock that stretches from Bryce Canyon to Zion and the Grand Canyon, attest to around 600 million years of geologic history. Each rock layer, each “step,” catalogues a different chapter in the Earth’s life as layer upon layers have been eroded, tilted, or uplifted over the years.

 

 

ZION NATIONAL PARK

Zion National Park lies along the edge of the Colorado Plateau and forms part of the geologic feature known as the Grand Staircase.

Over 240 million years ago, sediment from the surrounding mountains were deposited in Zion’s flat basin. The land and climate changed, resulting in a fluctuation of desert, coastal plains, and marine habitats—and sediments. The weight of the accumulated sedimentary deposits—over 10,000 feet of accumulated deposits—caused the basin to sink. Similarly, the process of lithification began as mineral-rich waters seeped through the compacted sediment. Limestone, mudstone, shale, and sandstone layers formed—each with their own chemical makeup.

The eventual uplift of the Zion region gave rivers greater force and rapidity. In effect, the North Fork of the Virgin River carved its way through thousands of feet of rock. Deep and narrow canyons and slot canyons formed, and the Virgin River continues its erosion and sedimentary excavation to this day.