The Earth Story

Head to the Navajo Nation in the southwestern US, for the story of the remnants of hundreds of uranium mines in this area.

Smoky mountain Located in Grand Staircase Escalante National Monument (see http://tinyurl.com/l6zwpew), a non volcanic mountain disgorges smoke and toxic gases into the clean desert air. The cause is a deep coal fire that started millennia ago that releases the toxic fumes that rise through fractures in the Cretaceous sandstones above. The rocks are the relics of the ancient shoreline of the inland sea that cut north America in half during the Mesozoic, recording the oscillations of marine and coastal sediments as it oscillated in size. Loz Image credit: David Rankin via EPOD

This one is a little heartbreaking. The caption tells the story:

Driving on and then over a Hogback, in the area that was just removed from Grand Staircase-Escalante National Monument, pending court challenges

Climb

This gorgeous picture of the Grand Staircase was captured last year by astronauts on the International Space Station. In Utah and Arizona north of the Grand Canyon, sedimentary rocks deposited between the Permian and the Cretaceous have been tilted slightly upwards, so that as they erode, resistant units create an enormous stairstep pattern across the entire region. Several amazing landscapes, including Bryce Canyon and Zion National Parks, are found along steps in the Grand Staircase. The Colorado River has then chopped its way through the heart of this landscape; today that river has been dammed to form Lake Powell and much of that lake is now visible in this shot.

The isolated peak towards the left is Navajo Mountain. The same sedimentary layers in the Grand Staircase have in this mountain been folded upwards by a laccolith; an intrusion of magma pushed the layers up into a dome (https://tmblr.co/Zyv2Js2AXb958).

Until late 2017, Grand Staircase-Escalante National Monument, encompassing much of this landscape, was the largest National Monument in the United States. The Secretary of the Interior has proposed cutting this monument in half.

-JBB

Image credit:

Previous post: https://tmblr.co/Zyv2Js2Sk2bgX

This arch is amazing and depressing. Original caption:

The Golden Cathedral An amazing interaction of rock, water and sunlight shimmers at this site in Neon Canyon, situated (at least for now) in Utah's Grand Staircase-Escalante National monument (see http://tinyurl.com/l6zwpew). Giant potholes in the rocky roof allow sunlight through, which reflects off the water and creates a beautiful pattern of glittering flickers of light on the surrounding rock. Loz Image credit:: John Fowler http://www.yourhikeguide.com/2013/02/28/golden-cathedral/ http://www.naturalarches.org/gallery-UTgoldencathedral.htm

This photographer gives some highlights of his recent trip to Grand Staircase-Escalante National Monument, on the verge of being cut in half.

Grand Staircase-Escalante National Monument, at least for now

Rocky mushrooms We have discussed these erosional features known as yardangs or hoodoos before (see http://tinyurl.com/pola5pm), but these examples from the Grand Staircase National Monument in Utah are particularly stunning. Loz Image credit: Steve Corey

Grand Staircase Escalante National Monument

Located in Utah, this wonderful desert landscape is but a part of one of the most famous series of geological formations on Earth: The Grand Staircase. These sedimentary stacks stretch from the Proterozoic two billion years ago, through the sequence of rocks that form the Gran Canyon (deposited from the Proterozoic to 250 million years ago), Zion National Park (240 to 90 million years ago) and Bryce Canyon (90 to the mid Cenozoic). Together these superimposed sequences form one of the best studied geological columns on Earth, covering most of the Phanerozoic Aeon. Named by geologist Clarence Dutton in the 1870's, it is one of Earth's more complete sedimentary records with 5 major steps, from which the geological history of Western North America has been reconstructed. They were all uplifted 1.5 to 3 km by the formation of the Colorado Plateau during the Laramide orogeny, and erosion has removed most of the post Cretaceous rocks, while recent volcanic rocks dot the entire area.

The Grand Staircase Monument is next to Bryce Canyon National Park, dominated by the north to south running ridge of the Kaiparowits Plateau, with steep slopes beautiful canyonlands to the east and a gentler descent to the west. Cliffs, plateaux, mesas, buttes, hoodoos and canyons dominate the landscape. Ranging from the early Triassic, through the Jurassic Navajo sandstone (forming the cliffs in the photo), followed by an ancient seaway and a lake, the layers peter out in the mid Cenozoic.

Numerous dinosaur fossils dating from the late Cretaceous ( 80 to 75 million years old) have been discovered in the area, including the recently announced oldest Tyranosaurid, nicknamed the King of Gore (which we covered at http://tinyurl.com/kvb2oue). The erosion pattern is favourable as there is more rainfall here than further south, which reveals new fossils for excavation at a faster rate and less forest cover hiding the rock exposures and destroying the fossils through root and soil bacterial action than northwards. In Utah there is just enough rain to erode rock, but not enough to support forests. These rocks have also told us the most of any worldwide about the patterns of changing ecosystems at the end of the Mezozoic era.

Petroglyphs from Native American groups also dot the area, including the Fremont and ancestral Puebloan peoples. Unlike most national parks, the monument is administered by the Bureau of Land Management.

Loz

Image credit: Bob Wick, Bureau of Land Management, California.

Geological cross section: http://en.wikipedia.org/wiki/File:Grand_Staircase-big.jpg http://www.utah.com/nationalsites/grand_staircase.htm http://www.utah.com/playgrounds/canyons_of_escalante.htm http://www.visitutah.com/parks-monuments/monuments-recreation/grand-staircase-escalante/_ _