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The Mystery of Sedona’s Red Rocks

Cathedral Rock, Sedona

Cathedral Rock, Sedona

Just got back from majestic Sedona, Arizona, where my family and I spent Thanksgiving. Sedona is a  charming and crazy amalgam of spectacular geology, amazing Fall foliage, exciting restaurants, and an eclectic mix of new age shops and centers. Believers of aura photos, energy vortices, and natural healing flock from all over the country to the countless psychic and supernatural shops in this beautiful town. Sedona may be infamous for its fortunetellers but deservedly famous for its amazing rock formations, which provided the backdrop for many Western movies, with stars from John Wayne to Clark Gable filming there.

Sedona’s rocks are also exciting for anyone interested in Earth’s past as they provide spectacular and rare insights into the Permian period (299 to 251 million years ago) when the Pangea supercontinent converged. At the time of Pangea, all continents on Earth joined together: one could have walked from the Northern American plate to the Australian, African, or even to the Antarctic plates.

Sedona and the soft rocks of the Supai Formation (red), below the young Coconino sandstone. Daniel Apai.

Sedona and the soft rocks of the Supai Formation (red), below the young Coconino sandstone. Daniel Apai.

Today, the rock formations cut across about 2,000 feet of Permian deposits: they consist of beautifully exposed wind-deposited (eolian) and coastal deposits. The amazing dark red rock layers that surround Sedona are part of the Supai Group: these interbedded layers have been deposited in the early Permian, when the Colorado plateau has been partly covered by an inland sea and a large desert. The inland sea has extended and receded many times during the early Permian; every time it receded the desert expanded and giant sand dunes covered the region that once was occupied by the sea. The shallow sea and the dunes left deposits that are different in color and deposit grain size; these layers of alternating colors make up the Supai group (seen as the mostly reddish, layered rocks in the photos). On top of the Supai group is the whitish/grayish Coconino Formation – a  younger, thick sandstone layer, deposited in the mid-Permian, in giant wind-blown dune fields (such locations are also known as erg, Arabic for sea of sand).

The soft red sandstone Supai group is easily sculpted by wind and rain erosion; harder sections of the Coconino formation on top of the red sandstone can protect somewhat the underlying the softer rocks, leading to the characteristic columns and spires typical to Sedona.

Although I have been to Sedona many times in the past, I somehow missed the Slide Rock State Park. This is a great location where flash floods have cut across the soft Supai sandstone and the creek now hosts a fast stream with beautiful pools — in the summer crowded with bathing families, but pleasantly serene in the Fall.

Ancient coastal and wind deposits surround Sedona.

Ancient coastal and wind deposits surround Sedona.

I may have missed the opportunity to have my aura photograph taken or to learn about my future from a Sedona fortuneteller, I can certainly understand the sense of magic this spectacular and serene scenery invokes in visitor – although for me, the true magic is not the mist in the crystal ball but knowing a bit about the incredible and distant past these majestic rock formation witnessed.

Sources:

[1] A Guide to the Geology of the Sedona and Oak Creek Area

[2] Ancient Landscapes of the Colorado Plateau

 

On to A New Year and New Exoplanets!

Grand Canyon Panorama

The 2014 year has brought much excitement in the field of extrasolar planets and 2015 is set to be at least as exciting as the past year: new powerful adaptive optics systems are searching the northern and southern skies for new exoplanets and Kepler2 should start bringing a large number of new planet candidates!

Just after Christmas my family took a break and visited the Grand Canyon, just a few hours drive from Tucson. I took the pictures from the South Rim’s Mather Point. Amazing to think how, in just about 5-10 million years, the apparently small Colorado river eroded away one vertical mile of rocks deposited over 1.8 billion years!

Back to the field, the first week of January also brings along the largest US meeting of professional astronomers, the winter meeting of the American Astronomical Society. This year astronomers are gathering in Seattle and we can take for certain that during the course of the next week there will be exciting announcements every day.

The large AAS meeting will be preceded by the open meeting of the NASA Exoplanet Analysis Group, where many in our field gather to review progress in exoplanet research and plan the next steps. The meeting will be broadcasted live, so you can watch it even if you are not in Seattle!

I wish everyone an exciting new year!

In just 5-10 million year the Colorado river eroded one vertical mile of mostly sedimentary rocks deposited over nearly two billion years.

In just 5-10 million year the Colorado river eroded one vertical mile of mostly sedimentary rocks deposited over nearly two billion years.