Jurassic Desert - A tour of the Colorado Plateau Part 1

The first time I visited the Colorado Plateau was in 1999. I had just started my first real job and had bought my first real car (a 1998 Chevy Cavalier). Two friends and I drove 30 hours straight from Edmonton to Moab, Utah in January. It was an eventful trip to say the least. The second time was with my family in 2019. Why keep going back? Because the Colorado Plateau is pretty amazing, especially if you like geology.

Driving north out of Phoenix (which is stupidly hot in the summer), you climb up 1700 m to reach the Colorado Plateau. That is where you find Grand Canyon National Park, Antelope Canyon, Petrified Forest National Park, Zion National Park, Canyonlands National Park, Arches National Park, Paria Canyon-Vermillion Cliffs Wilderness area, Grand Staircase-Escalante National Monument, dinosaur trackways, Meteor Crater Natural Landmark, and so much more! The plateau is a geological paradise, and you can hardly drive 20 minutes without running smack dab into some spectacular geology and views. The geological sites of northern Arizona and southern Utah are so plentiful, it isn't possible to cover them in a single post. This post (part 1 of 3) focuses on the 190 to 180 million year old Navajo Sandstone (1, 2) and the beautiful scenes it produces.

Three sites on the Colorado Plateau with spectacular views of the Navajo Sandstone (green) and the Petrified Forest National Park (orange; part 2 in the series). All are a must see!

The Colorado Plateau is basically a piece of uplift crust that was thrust up over a mile (1600 m). Because of this and over time, rivers have cut down through the sedimentary rocks of the plateau exposing some absolutely stunning landscapes that make for many iconic photos. Rivers cutting down through the plateau is what formed the Grand Canyon. During the Jurassic Period, the area that is now the Colorado Plateau was a huge dessert covered in massive sand dunes that might have looked something like the Sahara Desert (1, 2).

View of the Sahara Desert in western Morocco (image source: 3). This is probably what the western USA looked like 180 million years ago. The inset illustration shows a cross-section through a sand dune and how dunes migrate in the direction of the wind is blows. The dune migrates as sand grains bounce their way up the back of the dune and fall down the front.

The dunes that formed in the Jurassic desert show cross beds that indicate the direction the wind was blowing at the time. From this, geologists can start to understand what the climate was like and how wind patterns changed as the climate changed. The cross beds also make for some absolutely spectacular scenery and visits to Antelope Canyon, The Wave, and Zion National Park should be on everyone's bucket list!

Top left: Zion National Park (image source: 4), Top right: cross beds (about 4 to 5 m high) in the cliffs at Zion. Middle left: Lower Antelope Canyon. Middle right: Also Lower Antelope Canyon, but also one of Microsoft's screen saver images. Bottom: The Wave at Coyote Buttes and also a Microsoft screen image (image source: 5)

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Info Sources:

1) Freeman, W. E., and Visher, G. S., 1975, Stratigraphic analysis of the Navajo Sandstone: Journal of Sedimentary Petrology, v. 45, p. 651-668.

2) Peterson, F., and Pipiringos, G. N., 1979, Stratigraphic relations of the Navajo Sandstone to Middle Jurassic formations, southern Utah and northern Arizona: USGS.

3) Sahara Desert, Morocco | flowcomm | Flickr

4) Zion canyon | Wikimedia Commons

5) North Coyote Buttes - The Wave | meteonetwork.it