Sunday, July 24, 2011

Hoodoos and Satin Spar - geologic niceties in Palo Duro Canyon

Palo Duro Canyon, noted for the great beauty of its multi-hued strata, also hides several surprising geologic treasures. Georgia O'Keeffe wrote of the canyon, "It is a seething cauldron, filled with dramatic light and color." I couldn't agree more. Two of my favorites among all the wonders of the park are hoodoos and satin spar gypsum.

 The hoodoos I speak of are not related to voodoo nor are they any type of Halloween decoration!  They are a beautiful geologic structure created by differential erosion. You've most likely seen pictures of them at Bryce Canyon National Park in Utah, the strikingly sculpted towers of sandstone that look like fairy tale castle spires. Palo Duro too has hoodoos (this is soo much fun typing all these oos), although not in the number or complexity of structure seen in Bryce. The most famous hoodoo in Palo Duro, at the end of a hot and shadeless 6 mile (round trip) hike is the "Lighthouse," seen in the adjacent picture.  Ok, maybe hiking this in over 100 degrees wasn't the smartest thing to do, but you can't stop me from going to see rock! This beautiful 310 ft high hoodoo is actually a national natural landmark.  The top of the Lighthouse is part of the Triassic Trujillo Formation (see the last blog notes). It's a tough sandstone, resistant to weathering.  The older Triassic variegated Tecovas Formation forms the main part of the hoodoo and the rocks that use to surround it. These surrounding softer mudstones eroded much faster than her sandstone cap, leaving the lone beauty standing there for all to see. 

The red- and white-striped Spanish Skirts of the Permian Quartermaster Formation show lovely details when one climbs close enough to look.  Glittering white stripes of satin spar gypsum decorate the red sandstone beds.  Here in Texas, the shallow marine sea rose and fell.  During cycles of evaporation, gypsum, an evaporite mineral, formed on the edges of the sea. You can see the same process at Lake Meade in Arizona and Nevada. Evaporite minerals form the white line marking the older height of the reservoir. Gypsum precipitates first when the water evaporates, followed by the more familiar halite or salt. The satin spar form of gypsum grows as aggregates of fibrous crystals. Tiny vertical needles shine in the layers. Here's a picture of a single layer I saw sparkling in the ruffled red sandstone skirts in Palo Duro Canyon.  The obligatory scale coin gives you an idea of the size of this layer.  It's just one of the many jewels making Palo Duro one of the most beautiful places to visit in Texas.

Next up:     Bats in my Belfry: Carlsbad Caverns National Park

Tuesday, July 12, 2011

Palo Duro Canyon (Texas)

Hidden away deep within the vast panhandle plains is a wonderful Texas treasure, Palo Duro Canyon State Park. Driving down the road to the park, one sees miles and miles of prairie and farmlands. Suddenly a hint of what is to come shows up as we pass a small gully with lovely outcrops, just before the park entrance. Once inside, the magic begins! Breathtakingly beautiful, the Palo Duro Canyon is a colorful fantasy land of rock and wildlife stretching beyond where the eye can see!

Second in size to the Grand Canyon, Palo Duro reaches 120 miles long, 20 miles wide and 800 feet deep. Its story begins, like all other canyons, with uplift and erosion by water.  During the Laramide Orogeny (no, check the glossary link - it doesn't mean that!) 35 to 80 million years ago, Texas and the Rockies Mountains rose to new heights. After the Pleistocene ice age ending only several thousand years ago, the humble Prairie Dog Town Fork of the Red River (grander in the past) cut the canyon down to what we see today.

The technicolor rocks seen in the walls of the canyon encompass a vast amount of time. From the bottom up, we see the Quartermaster Formation (Permian 250 million years ago), the Tecovas and Trujillo Formations (Triassic 225 million years ago) and the Ogallala Formation (Miocene-Pliocene 4-10 million years ago).  One notes the missing time before the Ogallala, over 200 million years. Why there are no rocks for most of the Cretaceous and early Tertiary periods, no one is certain. It may be they were eroded or perhaps never deposited in this area to any extent. 

The photos shows a view downstream of the canyon and the stratigraphic section. The basal red rocks are the Quartermaster: beautiful alternating beds of red sandstone and evaporites, mostly white gypsum. One can see ripples formed in the shallow marine environment. The beautiful red and white striped and rippled rocks probably inspired the name these rocks are known by: "Spanish skirts." Above these are the variegated Triassic formations. Beautiful yellow, purple, gray, tan and other colors provide a lovely contrast to the rocks above and below. The lower multi-hued rock layer is the Tecova Shale subsequently capped by the Trujillo Sandstone forming a light-colored ledge. For the dino buffs, this marks the beginning of the age of the dinosaurs.  Palo Duro, at this time, was a swamp land filled with phytosaurs, amphibians and fish. Lastly,  the Ogallala crowns the canyon.  Rocky Mountain sediments form this beautiful formation mainly composed of siltstones and conglomerates, topped by  a caliche ledge with beautiful opal cementation.  Fossils in these rocks include animals similar to those you've heard of at the famous La Brea tar pits: mastodons, horses, saber-tooth cats, rhinos, etc.  The Pliocene and Triassic fossils can be seen in a nice exhibit at the visitors' center.

There's more than just rocks to see at Palo Duro Canyon.  Wildlife are abundant and very brave around campers.  Beautiful birds pose for your camera. Life is peaceful camping down in the canyon away from a bustling busy world. In nearby Canyon, there's a great museum:  Panhandle Plains Historical Museum. If you have a chance,  I highly recommend a visit to this geologic fantasy land. 

Next:  Hoodoos and Satin Spar - geologic niceties in Palo Duro Canyon

Saturday, July 9, 2011

Hello World!

Welcome to my very first blog. Alright, it's not very exciting. Stay tuned and you'll see some wonderful places to visit. My husband and I travel the world. It's odd but so many of our trips end up looking at rocks. So following my blog, you'll learn a little geology and see amazing places. Come along with us, metaphorically speaking, on our geology journeys around the world.