19-June-2008, 04:01 PM
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Established Member
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Join Date: Jan 2006
Location: Madison, Ohio
Posts: 1,701
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"New" dinosaur site in Utah?
From National Geographic
Quote:
Crowded with dinosaurs, petrified trees, and other prehistoric treasures, an ancient riverbed in Utah is surprising scientists.
The discovery sheds new light on a Jurassic landscape dominated by dinosaur giants that lived 145 to 150 million years ago
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The news story indicates that the locals new about this location and alerted the scientists to its presence. Well, all they had to do was read Charles B. Hunt's Geography of the Henry Mountains Region Utah USGS special paper 228 published in 1953.
Quote:
Moreover, the color of a bed may change laterally. A
considerable part of the clay seems to be bentonitic, is
probably of volcanic origin, and may be the source of the
silica that is now concentrated in the petrified wood
and concretions. The variegated clay member inspired
the picturesque name Pinto Hills for the belt of
country west of Hanksville.
Limestone concretions and thin beds of limestone
are present in the gray clay member and to less extent
in the variegated clay and Salt Wash sandstone members. Most are dense and light-colored, although a few are brown and earthy. They form low ledges in the badlands and weather into nodules. Short thick lenses of gravel in unconsolidated sand or clay matrix are found sparingly in the gray clay.
Some of the pebbles are 4 in. in diameter. Many are highly polished; many have minute parallel streaks. They may be gastroliths, or stomach stones of dinosaurs, but there is some question whether stomach stones would assume such polish and further doubt as to whether even a dinosaur would relish stomach stones as large as 4 in. in diameter, and in such large
quantities. Petrified wood and dinosaur bones are abundant
locally in the Morrison throughout the region. A very few pelecypod shells, presumably of fresh-water origin, were observed. .....Mode of deposition.-The Morrison formation represents river and lake sediments deposited upon a little
dissected and poorly drained surface. After some reworking of the Summerville formation, deposition began with a series of coarse clastic deposits. Rather vigorous stream action is implied by the gravels that
were deposited. The conspicuous channeling of the beds and the presence of logs in these coarse deposits suggests a flood-plain type of deposition.
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__________________
(By the way, I hate it that so many papers in the areas of planetary science and geology are not easily available to the dreaded "non-subscribers". It is like they are screaming at me: "YOU CAN'T HANDLE THE TRUTH". Good, I feel better now.)
"Quaerendo inventis"
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