Tuesday, September 19, 2017

Grand Canyon, North Rim, Arizona

The Grand Canyon North Rim was not on my original itinerary, but I adjusted it to make a side trip there.  It is 80 miles from Kanab, and took us 1-1/2 hours to drive there, but I am glad we did. The day we were there it was so windy it blew hats right off of heads, and also had a chill in the air. It was also kind of hazy, but still beautiful. The drive into the North Rim area was via Hwy 67 and ended at the Grand Lodge. We stopped there for a while to view Bright Angel Point, have lunch at the Lodge and sit on the patio with a view of the canyon. There are a few places that they allow dogs, which includes the Lodge, Saloon, the patio, and the path that runs next to the parking lot.  They could not go on the Bright Angel Point trail; as you can see from these pictures, it was a very narrow trail.


The trail is 1/2 mile long going to a spectacular view of the Grand Canyon. The view below shows the Earth's crust fractured, lifting one side of the rock layers and lowering the other, creating a fault. Water follows this fault, as well as the North Kaibab trail. Springs, like Roaring Springs, are able to flow because the groundwater has reached impermeable rock, where it spreads out sideways and leaks out of the canyon walls as springs. (I guess this is what was occurring in Idaho when we visited Ritter Island.)

There is only this one trail that leads from the Grand Lodge and Visitor Center. From here we had to get back in the truck and drive back to Cape Royal Road, which is a 20 mile drive to the end of the road at Cape Royal. There is one side road to Point Imperial, which we did on the way back out.

This viewpoint was called Roosevelt Point. It was named in honor of Theodore Roosevelt, 26th President of the United States for his efforts towards the preservation of the Grand Canyon. 

Looking east, the opposite side of the Grand Canyon lies far below. This entire region, 75 million years ago, was a smooth plain stretching off to the east. About 5 million years later, that landscape began to change. North America drifted westward, squeezing the western landscape, and the land began to rise. Far to the east, the Rocky Mountains folded and buckled skyward. Here, on the Colorado Plateau, the uplift was smoother. Even so, the Kaibab Plateau where I took these pictures, was pushed about 2,400 feet higher than the Marble Platform to the east, creating a big step down.

The big hole in the side of the rock is called Angel's Window. Looking through the window, the Colorado River can be seen far below. During the uplift of the Kaibab Plateau, stress and strain caused the rock to fracture forming vertical joints that intersect the horizontal bedding planes. Weathering (rain, freezing and thawing) along these planes and joints has eroded a hole in the Kaibab limestone and enlarged it to form the window.

We then walked the Cape Royal Trail past Angel's Window to the end of the trail.

The North Rim receives up to 12 feet of snow each winter, while the South Rim gets about 5 feet of annual snowfall. The Colorado River has given the Grand Canyon its depth (1 mile), while side stream erosion has given the canyon its width. Water is the most powerful force acting on the canyon today. This is especially apparent on the North Rim, where the landscape is a maze of jutting side canyons, rock islands, and horseshoe-shaped alcoves. The North Rim has eroded more than 7 miles from the river's edge, while the South Rim has only retreated 3 miles. Why? Because the North Rim is higher than the South Rim by 1,200 feet and captures twice the amount of rain and snow. Since the plateaus are higher to the north, water from the North Rim runs south into the canyon, causing greater side canyon incisions. Water on the South Rim runs south too, away from the canyon, resulting in less erosion and a stepper profile (see below).

Also, if you look at the canyon, they appear to resemble ancient temples towering above the river. Geologist Clarence Dutton named many of the canyon's formations temples, after Eastern religious and spiritual deities like Shiva and Vishnu. Cliffs, slopes, alcoves, plateaus, mesas, buttes, terraces, and platforms all make up what we call temples in the Grand Canyon. Temples form when side canyon erosion produces peninsula-like projections off the main rims, like here on Cape Royal. Further erosion transforms the peninsulas into islands, like Wotans Throne, and separates them from the rim, like Vishnu Temple. Erosion continues, as softer rock erodes and undercuts harder rock, until the temple is gone. 

The view from Cape Royal extends across the canyon and may reach 100 miles on a clear day. Sometimes the view within the canyon is hidden or murky. When winds are calm, cold air can drain into the canyon and become trapped. If moisture in the cold air is high enough, clouds may form in the canyon, with only the rims and highest temples poking through.  Less appealing are the times when the cold air carries air pollution into the canyon from nearby industries or forest fires. Fire managers try to avoid such smoke impacts, but sometimes it happens. Human industry tries to lessen their impacts too. One nearby coal-fired power plant invested hundreds of millions of dollars to reduce its contribution to these haze layers that get trapped in the canyon.

As we headed back out of the canyon we took the 3 mile side road to view Point Imperial. This is the highest viewpoint in the park at 8,803 feet. There is no visible basement rock in the rock layers -- the river has not cut that deeply yet. 

Prominent in the middle view are the Supergroup rocks, the middle rock layers of the canyon often absent or obscured. The distant Marble Platform is a 2,700 foot step down from Point Imperial. Though not visible from here, the Colorado River is about 7 miles from this point. The river meanders its course more than a mile below this elevation. 

In this picture view you can see the Mesozoic rocks of the Vermillon and Echo cliffs, where the nearest dinosaur fossils are found. No dinosaur fossils have been unearthed in Grand Canyon, but that does not mean dinosaurs never roamed here. Mesozoic rock layers -- a mile thick -- once covered the canyon's Kaibab limestone layer, which is the rock where we were standing. When the Kaibab Plateau rose up 70-40 million years ago, the soft overlaying Mesozoic rock cracked, broke, and eroded away. Like hosing mud from the hard-surfaced Kaibab limestone, washing away all evidence of dinosaurs.

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