Geology of the Grand Canyon area

Geology of the Grand Canyon area

All rights reserved. Sunrise over Mount Hayden in the Grand Canyon. To the untrained eye, the Grand Canyon might just look like one big hole in the ground. But to some scientists, the American Southwest’s iconic gorge is increasingly looking like several ancient canyons of different ages, stitched together by erosion that occurred about six million years ago, and subsequently sculpted into its modern form. A new study published in the journal Nature Geoscience , added to more than a century’s worth of fieldwork, is helping researchers decipher a geological tale that began unfolding when dinosaurs roamed the landscape. For nearly years, scientists have been debating how and when the Grand Canyon formed, says Karl Karlstrom , a geologist at the University of New Mexico in Albuquerque. In recent decades they’ve mostly split into two camps: those proposing a “young canyon” model in which the Colorado River alone carved much of the gorge in the past five million years or so, and those suggesting an “old canyon” model in which a series of ancient rivers carved ancestral canyons along more or less the same route.

Cambrian Sixtymile Formation of Grand Canyon yields new findings

It is not the widest nor longest nor deepest canyon in the world, but the Grand Canyon of northern Arizona is certainly one of the most impressive and most visited natural wonders found on the planet. Photographs, no matter how spectacular, cannot capture nor prepare one for the awe-inspiring sight of viewing the immensity of this canyon for the first time. Neophytes to the canyon have been known to shed an emotional tear as they initially stand in awe before its colossal grandeur.

Fortunately for all mankind, early political leaders saw its limitless natural value to science and the soul of mankind and preserved this special grand place of earth as a national park years ago, on Feb.

Written by Wayne Ranney, author of Carving Grand Canyon: Evidence, Theories from the canyon’s rocks, the age of the canyon becomes more of a puzzle. Traditionally, the age of the canyon is ascribed at 6 million years but this date refers.

The geology of the Grand Canyon area includes one of the most complete and studied sequences of rock on Earth. Most were deposited in warm, shallow seas and near ancient, long-gone sea shores in western North America. Both marine and terrestrial sediments are represented, including lithified sand dunes from an extinct desert. There are at least 14 known unconformities in the geologic record found in the Grand Canyon. In total, the Colorado Plateau was uplifted an estimated 2 miles 3.

A drainage system that flowed through what is today the eastern Grand Canyon emptied into the now lower Basin and Range province. The new river captured the older drainage to form the ancestral Colorado River , which in turn started to form the Grand Canyon. Volcanic activity deposited lava over the area 1. The end of the last ice age and subsequent human activity has greatly reduced the ability of the Colorado River to excavate the canyon.

Dams in particular have upset patterns of sediment transport and deposition. Controlled floods from Glen Canyon Dam upstream have been conducted to see if they have a restorative effect. Earthquakes and mass wasting erosive events still affect the region. At about 2.

In Photos: Stunning Views of Grand Canyon National Park

To mark this occasion, here are some facts about one of the world’s most amazing natural landmarks. It was formed by water erosion of the Colorado River. It is believed the river made its course through the canyon about six million years ago.

to how the Grand Canyon that visitors see today was actually formed. Modern technology and rock-dating techniques have begun to provide.

The Grand Canyon is a mile-deep, mile wide, mile long 1. The colorful spires, the rocky cliffs, the hidden pocket canyons, the pristine springs laying down lovely deposits, the roaring thunderstorms and arching rainbows are to many the quintessence of the U. When the author, his cousin Chuck, and his sister, Sharon, were hiking the Bright Angel Trail from the North Rim into the canyon, a snake crossed the trail and slithered into some dry grass just at the trail edge.

Sharon, just behind, was not aware of the snake until it stuck its head out and rattled the grass just at her feet. Deciding that discretion was the better part of valor, and that if it rattles like a rattler it might actually be one, she made one mighty leap backward, landing in a cloud of dust on a switchback below. Sharon almost certainly was not concerned with the rocks about her at that instant, but she had leaped backward through history.

And what a history it is. At the bottom, the inner canyon is cut through the Precambrian Vishnu and Brahma Schists. The older Vishnu has the appearance and chemical composition of metamorphosed sediments.

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Slopes of Dox Formation near Unkar Creek. How was it formed? The truth is that no one knows for sure though there are some pretty good guesses. The chances are that a number of processes combined to create the views that you see in todays Grand Canyon. The most powerful force to have an impact on the Grand Canyon is erosion, primarily by water and ice and second by wind.

Other forces that contributed to the Canyon’s formation are the course of the Colorado River itself, vulcanism, continental drift and slight variations in the earths orbit which in turn causes variations in seasons and climate.

PDF | The age and evolution of the Grand Canyon have been subjects of nine sites in the Grand Canyon showed uranium-lead dating evidence for an old These are important geologic constraints that must be honored in any model of the.

The Grand Canyon is one of the supreme geologic laboratories on Earth and, after about years of geologic investigation, one might think that its secrets have been mostly resolved. This is especially true of the flat-lying layered rocks that are so visible from both rims within Grand Canyon National Park. Nearly five decades ago, in the late s, was the last time a new formation was discovered and defined in the Grand Canyon with the discovery of the Surprise Canyon Formation.

Their research paper, recently published in Nature Geoscience , titled “Cambrian Sauk transgression in the Grand Canyon region redefined by detrital zircons”, found the Sixtymile Formation sandstone to be much younger than previously thought. This unit occurs in only four outcrops in a remote and relatively inaccessible section of eastern Grand Canyon. The Sauk marine Transgression occurred during a period of time dating from the to million years ago when the sea level rose across North America leaving behind zircons, commonly found in sand, that contain trace amounts of uranium and thorium mineral deposits within specific sedimentary units enabling researchers to date the deposits.

The age of Tonto Group of Grand Canyon, just overlying and hence younger than the Sixtymile Formation, was the serendipitous discovery. These layers record the marine transgression that inundated North America from its margins to the middle part of the continent Missouri and Oklahoma. Think of it as what might happen today to the relatively flat continent of Australia if sea level rose or the continent subsided several hundred meters.

19.2 Relative Dating Methods

T o stand on the South Rim and gaze into the Grand Canyon is to behold an awesome immensity of time. The Colorado River has incised a km-long chasm that in some places is 29km wide and 1. Visitors to Grand Canyon National Park will learn that scientists believe the canyon is about 6m years old, relatively young by geological standards.

Now a few scientists want to call time out. The canyon is not 6m years old, they say, but more like 70m years old.

An unconformity is visible in the Grand Canyon (Figure , white dashed line) above Proterozoic rocks that were tilted and then eroded to a flat surface prior.

Deep inside the Inner Gorge of Grand Canyon, northern Arizona, are the crystalline basement rocks that probably date back even to the Creation Week itself. Clearly visible in the canyon walls are the light-colored granites, such as the Zoroaster Granite, which are stark against the darker, folded strata of the Vishnu Schist and the other metamorphic rock units of the Granite Gorge Metamorphic Suite 1 see lowest purple and green shading in diagram.

These are former sedimentary and volcanic strata that have been transformed by heat and pressure, possibly during the intense upheavals when the dry land was formed on Day 3 of Creation Week. These were originally basalt lava flows several meters to tens of meters thick. In some outcrops pillow structures have been preserved, testimony to the basalt lavas having originally erupted and flowed under water onto the Creation Week ocean floor.

Metamorphic rocks are not always easy to date using radio-isotopes. Results obtained usually signify the “date” of the metamorphism, but they may also yield the “age” of the original volcanic or sedimentary rock. The “age” or “date” is calculated from the amount of the daughter isotope produced by radioactive decay of the parent isotope. In Grand Canyon, the “date” of metamorphism of the basalt lavas to form these Brahma amphibolites has been determined as Ma million years ago , based on U-Pb dating of minerals in the overlying Vishnu Schist and underlying Rama Schist that formed during the metamorphism.

These included seven samples from a meter long and 2 meter wide amphibolite body outcropping just upstream from the mouth of Clear Creek at river mile 84 measured from Lees Ferry. All 27 samples were sent to two well-credentialed internationally-recognized, commercial laboratories for radioisotope analyses—potassium-argon K-Ar at a Canadian laboratory, and rubidium-strontium Rb-Sr , samarium-neodymium Sm-Nd , and lead-lead Pb-Pb , at an Australian laboratory.

How Old Is the Grand Canyon?

Its banded walls make up one of the most magnificent landscapes on Earth. And yet it seems the only time reporters bother to mention its geology is when they are writing about creationists and their bogus claims that the Grand Canyon formed a few thousand years ago. It’s a shame, because the real story of the Grand Canyon is a riveting epic.

Even its scientific history is fascinating: Figuring out just how old the Grand Canyon is has challenged geologists for years.

Rock falls frequently take out sections of trail in the Grand Canyon requiring the By dating the fossils found in the rock of the Kaibab Limestone, geologists.

The canyon itself is made up of rock layers that are millions and, in some cases, billions of years old, with each layer representing a different geological time period. But the actual carving of the canyon and when it began to resemble the Grand Canyon as we know it today is a bit harder to pin down. One thing geologists can agree on is the age of the layers of rock that make up the walls of the Grand Canyon.

The youngest layer of the canyon—the Kaibab—is million years old, while the oldest layers date back as far as 1. This may seem like a long time ago, but it is actually quite recent if you consider the full timeline of the Grand Canyon. The Grand Canyon was formed over a long period of time by erosion and downcutting. Downcutting is the process by which a river cuts down into and erodes the layers of rock to form a canyon.

Geologic and Related Photographs of the Grand Canyon Region (1967–2010)

Have you ever been to the Grand Canyon before? What I always liked about going there was counting all the layers of rock along the steep-sided canyon. For instance, they reveal stories about colliding continents , meandering streams and volcanic eruptions.

Grand Canyon May Be As Old As Dinosaurs, According To New Geologic Dating Study. Share.

Most scientists agreed that the Grand Canyon was carved 6 million years ago, until a study in used new data to argue that the canyon was actually 12 times as old. A new study tries to merge the old and new data into a single story. January 27, The debate over the age of the Grand Canyon has raged for over years: It’s old! It’s young! It’s really, really old! It’s not as old as you think! Back when dinosaurs were wrapping up their time on Earth, rivers were carving a path through what is now Arizona.

Time passed, the rivers dried up, and the canyons stood, dry and empty, for tens of millions of years. Not too far away, another canyon was carved, about 20 million years ago. Then, just 6 million years ago, snowmelt from the Rocky Mountains began seeking a path to the ocean, and the rushing water took advantage of these canyons as it headed west to the Pacific, ultimately becoming the Colorado River.

Though they are still working out some of the details — maybe groundwater, not snowmelt, drove the creation of the Colorado River? Maybe caves played a role?

7 Geologic Time

When asked to imagine the biggest, deepest, longest canyon one can imagine, an image of the Grand Canyon will often pop into a person’s mind. The Grand Canyon is a site of almost unfathomable grandeur, which inspires awe in anyone who sees it. Lately, however, the canyon has also inspired controversy, specifically over its origins. It is generally held by the scientific community that the Grand Canyon formed by the slow erosion of the Colorado River over millions of years.

Steve Austin, however, has proposed an entirely different theory on the age and formation of the canyon and wrote a book explaining his theories titled Grand Canyon: Monument to Catastrophe. Austin believes that the canyon was formed extremely rapidly during the period immediately following the global flood of Noah in the biblical book of Genesis.

The Redwall Limestone in the Grand Canyon is a water soluble rock, found in the Grand Canyon are nearly 12, years old and date to the.

There are a number of lava flows on the plateau that the canyon is cut into yellow in Figure 1, above. These lava flows are Cenozoic in age, and some of them spill into the canyon. The walls of the canyon are mostly cut into horizontal rock layers of Paleozoic age green in Figure 1, above. There is an angular unconformity at the bottom of the Paleozoic layers. An angular unconformity is the result of tilting and eroding of the lower layers before the upper ones are deposited. These tilted and eroded layers are Precambrian in age blue in Figure 1, above.

The geological relationships of the various formations are quite clear. The lava flows which spill into the canyon must be younger than the canyon. The canyon must be younger than the rock layers that it cuts into. The sediments above the angular unconformity must be younger than the sediments below it. Even young-earth creationists would agree with this relative sequencing of events. They would argue for a much shorter absolute timescale than mainstream geologists would accept, but the relative sequence is agreed upon by all parties.

Grand Canyon ‘may date back to the era of the dinosaurs’

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Ancient Grand Canyon rocks provide new insights into continental flooding Canyon, which have traditionally been difficult to precisely date.

After years as a national park and eons as a geological wonder, the American icon continues to reveal layers of its past and of the landscape ahead. Teddy Roosevelt called the Grand Canyon one of the great sights that every American should see. But the history of the mile-long canyon runs much deeper. Humans first encountered it some 12, years ago, as the earliest Americans spread across the continent. By the 16th century a few Spanish explorers began passing through.

Today the Grand Canyon hosts 6 million visitors a year, making it the second-most visited US national park after the much more accessible Great Smoky Mountains. Among the new discoveries are updated ages of one of the most important rock layers in the canyon, a finding that shifts key points in its geologic history.

Reading rock strata – Layers in the Grand Canyon


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