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THE QUARRY 2
THE DINOSAURS 3
First Discoveries 3
Position of Dinosaurs Among Reptiles 4
Geologic History 4
What They Looked Like 6
Temperature Tolerance 10
Gizzard Stones 11
THE CLIMATE, LIFE, AND LANDSCAPE OF JURASSIC TIME 12
How Do We Know? 14
ANIMALS FROM THE QUARRY 15
Why So Many? 19
How Were They Preserved? 21
How Were They Exposed? 24
WHY DID DINOSAURS BECOME EXTINCT? 25
HISTORY AND DEVELOPMENT OF THE QUARRY 26
Discovery and Early Years 26
Starting the Quarry 28
Extent and Development of the Find 28
Work Methods 32
Further Development 34
Protecting the Quarry 35
Present Development 37
THE SCENE TODAY 38
KEY TO PRONUNCIATION 46
SUGGESTED READINGS 47
[Illustration: JURASSIC LANDSCAPE SHOWING ANIMALS AND PLANTS THAT
LIVED HERE DURING MORRISON TIME. (FROM A PAINTING BY ERNEST
UNTERMAN.)]
[Illustration: Spade and Pick]
As you approach Dinosaur National Monument from Jensen, Utah, you see
the mass of Split Mountain and the deep, short canyons that scar its
south slope near the Green River’s gorge. As you cross the National
Monument boundary the grand view is lost and you begin to notice
details. The masses of gray shale that seem to be carelessly piled
against the tilted sandstone layers are bare of vegetation. The ground
between the hills and the Green River is covered with sagebrush and
greasewood, while along the river itself are a few large cottonwood
trees and many bushes. A sharp turn brings a change of scene as your car
enters a portal in the wall you have been following. The pronounced tilt
of the rocks becomes more obvious.
A final steep climb and the visitor center is at hand. This building
encloses a significant part of the Dinosaur Quarry, perhaps the greatest
deposit of fossil dinosaur bones known today. From this quarry have come
many of the dinosaur skeletons that are seen today in our great museums.
After parking, a short walk to the overlook on the southeast reveals a
splendid view of Split Mountain. Between that broad arch of eroded
sandstone and the quarry lie steeply tilted sedimentary rocks of various
compositions and hues. Buff and gray sandstones that weather into soft
shapes are separated by reddish-brown shale. Directly to the east is a
section of varicolored shale whose pastel pinks, reds, greens, grays,
and whites justify the name of “rainbow beds” that was given them by
geologists. In the upper part of this section are hard sandstone and
limestone layers that resist the erosive action of wind and water. They
stand higher than the softer shales and form hogbacks that rim Split
Mountain.
One of these layers can be traced across the ravine immediately east of
the parking area into the sandstone ledge that forms the north wall of
the visitor center. This is the famous Dinosaur Ledge.