e Como Bluffs
are about ten miles south of the Bone-Cabin Quarry; between them is a
broad stretch of the Laramie Plains. The exposed bone layer in the two
localities is of the same age, and originally was a continuous level
stratum which may be designated as the "dinosaur beds;" but this
stratum, disturbed and crowded by the uplifting of the not far-distant
Laramie range of mountains and the Freeze Out Hills, was thrown into a
number of great folds or rock waves. Large portions, especially of the
upfolds, or "anticlines," of the waves, have been subsequently removed
by erosion; the edges of these upfolds have been exposed, thus
weathering out their fossilized contents, while downfolds are still
buried beneath the earth for the explorers of coming centuries.

Therefore, as one rides across the country to-day from the bluffs to
the quarry, startling the intensely modern fauna, the prong-horn
antelopes, jack-rabbits, and sage-chickens, he is passing over a vast
graveyard which has been profoundly folded and otherwise shaken up and
disturbed. Sometimes one finds the bone layer removed entirely,
sometimes horizontal, sometimes oblique, and again dipping directly
into the heart of the earth. This layer (dinosaur beds) is not more
than two hundred and seventy-four feet in thickness, and is altogether
of fresh-water origin; but as a proof of the oscillations of the
earth-level both before and after this great thin sheet of fresh-water
rock was so widely spread, there are evidences of the previous
invasion of the sea (ichthyosaur beds) and of the subsequent invasion
of the sea (mosasaur beds) in the whole Rocky Mountain region.

In traveling through the West, when once one has grasped the idea of
continental oscillation, or submergence and emergence of the land, of
the sequence of the marine and fresh-water deposits in laying down
these pages of earth-history, he will know exactly where to look for
this wonderful layer-bed of the giant dinosaurs; he will find that,
owing to the uplift of various mountain-ranges, it outcrops along the
entire eastern face of the Rockies, around the Black Hills, and in all
parts of the Laramie Plains; it yields dinosaur bones everywhere, but
by no means so profusely or so perfectly as in the two famous
localities we are describing.

_How the Skeletons Lie in the Bluffs and Quarry._ At the bluffs single
animals lie from twenty to one hundred feet apart; one rarely finds a
whole skeleton, such as