Expeditions: Ravens Ridge --
Rio Santa Barbara --
Pecos Wilderness (Hamilton Mesa) --
Rio Chama --
Rio Chama, early October:
Errand list for a drive up the river: finally take a picture of the
Great Scenic Moment... visit the dinosaur museum at Ghost Ranch...
go on quest for the Perfect Cottonwood.
Just above Abiquiu the highway climbs and you can see back down the
valley of the Chama River. Physiographically we are climbing from the
Espanola Basin up onto the Colorado Plateau margin, with the sudden
appearance of red Chinle rocks to the right of the highway to herald it.
Chinle mudstones of Pictured
Cliff formation, with Entrada sandstone above.
The Chinle rocks are late
Triassic age, something like 215 million years old (see Karen Strom's geological
time-chart), and the smooth Entrada sandstones are middle Jurassic,
160 million years old. Or so. In between, 40-million-odd years of other
events happened, but the rocks here don't tell us about it.
The very white layer on the background skyline is the Todilto formation,
late Jurassic, of limestone and gypsum deposited by evaporation from the
warm, shallow, equatorial sea that lay here when "here" was somewhere
down near the equator.
Right now, "here"
is by milepost 223 on
US Highway 84, and the bright red Petrified Forest Formation mudstones
make a clear contrast with the buff-colored cliff-forming Entrada
The dinosaur quarry at Ghost Ranch is actually in the Rock Springs
Formation, a Chinle layer missing from the
sandwich in these photos. It would lie just above the Pictured Cliff
formation. From this famous quarry, only a few miles from the outcrop
above, came a beastie called, well, there's some question about its
right name, Coelophysis or
Rioarribasaurus; but no question about the beautiful,
"fully-articulated"--meaning the bones are all there and in proper
relation to each other--six-foot skeletons, which have been excavated
there, now carefully picked out from the rocks they had rested in for
200 million years. At the Ruth Hall Museum at Ghost Ranch is a ten-foot
skeleton still being worked on. The online Museum of Paleontology at UC
Berkeley has a beautiful photo of Ghost Ranch's carefully
exposed specimen, at Coelophysis.
Here's a young
Here's a drawing of
Coelophysis/Rioarribasaurus, on the New Mexico Museum of Natural
History's Dinosaurs in New
Past Ghost Ranch, the highway swings away from the river and climbs up
again, northwards to Tierra Amarilla and Chama. A long dirt
road, a car-eater in many seasons but firm and dry today, follows the Chama
River west between the cliffs of the Rio Chama Wilderness, to dead end
(for all but river rafters) at the monastery at Christ in the Desert. I wanted to
find a perfectly shaped, perfectly yellow cottonwood with the
river in the foreground and cliffs behind ... and then sit right there by
the river, to listen to the water flowing by.
....... . . . . sit right here by the river and listen to
the water flowing by.
Expedition October, 1995.
Page updated, January 12, 2000.
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