Thursday, June 6, 2019

Painted Desert, Petrified Forest

5 June 2019

Day 11
We left Gallup, NM, and headed west on I-40 again.  We took a little diversion south though to drive through (and walk around) the Painted Desert and then the Petrified Forest.

The Painted Desert looks like the set from a sci-fi movie.  Really, it starts out with somewhat normal reddish brown rolling hills.  They turn into sort of layered red and white hills and bluffs, looking vaguely like red velvet layer cake.  The reds give way to dark brown hills with powdered sugar white minerals dusted on the top.  And the dark brown fades into greys and beiges alternating with blue-grey and purple-grey layers.  Some of the hills and cones are smooth, others are corrugated and rippled.  The place really looks unearthly!

This is one of those instances where the information from the site makes more sense than me trying to explain and paraphrase, so here are the facts, figures, and history from the informative signs around the Painted Desert & Petrified Forest National Monument:

"As you look out over the Painted Desert, you are only seeing a small portion of it.  The Painted Desert extends over 7,500 square miles (19,425 sq km) - about 120 miles (190 km) long by 60 miles (97 km) - across northeastern Arizona.  Because Petrified Forest National Park lies at its heart, the entire park contains the colorful rocks of the Painted Desert.  These particular mudstone and sandstone rocks are called the Chinle Formation and were deposited from 227 to 205 million years ago during the Late Triassic Period.  During that time. the supercontinent Pangaea broke apart, eventually forming our present continents.  Over the next 180 million years, the rocks of the Chinle Formation were deeply buried, uplifted, and eroded into the badland topography you see today.  Approximately 20 million years of Late Triassic rock and fossil history are recorded in this geologic kaleidoscope.

"The Chinle Formation consists mainly of sandstone and mudstone layers which were deposited by a vast river in a forest ecosystem.  Geologists group these layers into members, which together make up the formation.  Older members are at the bottom of the column, with youngest at the top.

"All of the colors you see are caused by iron in the sediments.  During deposition, drier climates allow the minerals to be exposed to oxygen, rusting the iron and creating red, brown, and orange colors.  Wetter climates can "drown" the sediments, allowing little or no contact with oxygen, causing the layers to be blue, gray, and purple."

There was an amazing "bridge" that really is a fallen tree that became petrified wood - and the mineral content actually makes this former tree a bridge of agate!!!

"Water created Agate Bridge and will destroy it.  The fossilized tree that now forms Agate Bridge grew in a lush subtropical forest 217 million years ago.  When this tree died, it washed into a river and its quick burial by river sediments prevented decay.  Volcanic ash dissolved in groundwater provided silica, which reacted with the log and slowly crystallized into quartz.  Millions of years later, rivers and streams eroded massive layers of rock strata to expose this fossilized tree.  Inevitably, water now carving the small gully under Agate Bridge will cause its collapse.  The supportive concrete span, constructed in 1917, is a tenuous attempt at preservation.  Water will always have its way."

"Nowhere else has so large and beautiful in every way wonderful [a] section of the ancient...forests been discovered, and after it is cared for by the Nation and made easily accessible, it will, I am sure, become one or the most attractive and famous places in all our Western Wonderland."  -John Muir, September 12, 1906

"Jasper Forest contains one of the largest accumulations of petrified wood in the world.  Originally called the "First Forest," this site was the first petrified wood site available to railroad travellers in the early 1900s.  Looking down you can see pieces of logs that were once encased in the sandstone ledge at your feet.  A visitor in 1917 wrote, "It was 6 miles to Forest #1.  It was well worth the trip tho [sic] for it is a wonderful sight...The ground was covered with broken pieces ...of the high and bright colored stuff."  Although Jasper Forest is no longer a visitor's first stop, you can still behold the same impressive sights, wonder at the vast deposits of colorful wood, and retrace the steps of those bygone travellers."

"I hardly dare write the words, but truthfulness compels me to say that in the Petrified Forest, the Grand Canyon, on the score of interest, has a rival."  -Horace Howard Furness, 1906

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