Forest of Rocks

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Clouds in the sky move about like tectonic plates on the earth.  Only long time separates obvious from the obscure.   

I drove from Flagstaff, Arizona to Gallup, New Mexico, via Petrified Forest National Park.  And there, lying all over the ground are logs made of rock.  They seem begging us to discover how they look like logs but are made of solid rock.  Walt Disney could not have made more realistic logs.  So let’s give it a shot: 

You can still see the knots in this log

The Triassic was the first period of the Mesozoic Era.  That’s a way of saying that it happened between 251 million and 199 million years ago.  After the greatest mass extinction of all time, at the end of the Permian, 250 million years ago, a forest grew here.  That’s when these rock logs were living trees.   

The late Triassic is best known for the rise of dinosaurs.  Eventually they replaced all those extinct monsters of the Permian. Thirty million years later, at the beginning of the Jurassic, dinosaurs dominated the earth, and survived for the next 180 million years.  Back then, almost every large animal was a dinosaur.  Some of their fossils were found here in Petrified Forest.

These logs were living trees about 216 million years ago.  They died and fell into a river, and got buried under layers of sediment that protected them from decay.  Ground water carried silica into the logs, cell by cell, replicating their structure in almost perfect detail.   The silica became hard quartz and took on many colors.  These logs are made up of almost solid quartz

All this happened while tectonic plates were moving about on the earth, shifting the rock of these fossils some 2100 miles to the northeast, from its tropical origin where Costa Rica is today, to Petrified Forest National Park.  Erosion then stripped away the softer materials around these relics, revealing their unlikely past for easy viewing today. 

In the above description I have reworded science-talk from experts, but I think it’s pretty close to the truth as we know it.  Truth, of course, is not always what we think it is, so I welcome your comments, especially if you love geology as I do.

I wonder what native Americans thought about these improbable logs when they inscribed these figures on a nearby cliff.  

Later in this trip, we will move further back in time to that lush fauna of the Permian, which in its dying, allowed modern life forms to grow. 

Please see a map of the places where I have slept, as updated each day by Michael Angerman:  Sharon in West Texas