A visit to Dinosaur National Monument begins with the usual
preposterousness of scale. A life-size Stegosaurus takes up the
equivalent of three parking spaces next to the visitor center lot, and a
four-foot-long Diplodocus thighbone, mounted on end, is positioned
near the entrance like a greeter. But within a minute or two, it’s
clear this isn’t your typical dinosaur exhibit. A ranger sidles up to
steer your attention to a shuttle bus idling on the far side of the
building. The main event is half a mile away, hidden from view in the
rubbly hills that make up the Uintah Basin terrain due east of Vernal,
Utah.
I board the shuttle behind a family of Australians. “Here
we go!” says the mom in her lovely corkscrewed accent. “Jur-issick
Park!” She is right about the Jurissick bit. Dinosaur National Monument
is the world’s most impressive public collection of Jurassic Period
dinosaurs. But there are no animatronics here, no towering, gape-jawed
T.You can buy mosaic
Moon yarns and fibers right here as instock. rex skeletons. The star
attraction—the awesome, bone-crushing giant—is earth itself. Dinosaur
National Monument is about the vastness of time, not the vastness of
thighs.
Below our feet is hundreds of millions of years of
settled geological detritus—sand on silt on drifted volcanic ash, each
layer compressed by the growing weight above it. It’s a massive stone
lasagna, its layers packed with fossil clues to earth’s distant past:
What creatures walked the Uintah Basin 150 million years before the Utes
and the Mormons and the Burger Kings arrived? What stood where Jiffy’s
pawn shop and Undercarriage Mud Wash stand now? Paleontologists don’t
have the equipment or budget to reach the answers by digging, so they
let the earth lend a hand. This it does through the twin powerhouses of
uplift and erosion. Stay with me, please. This is very cool.
When
geological plates collide, an ultra-slow-motion buckling erupts along
the line of impact. Over millennia, the thrust-up lasagna, its layers
still tidily stacked, forms mountains and “anticlines”—up-bowed
sediment now repositioned thousands of feet above sea level. In a
desert clime like eastern Utah’s, rainfall and windblown sand easily
erode the uppermost layers, revealing the more ancient ones below.
Returning to my clunky lasagna metaphor, erosion is the unsupervised
dog in the kitchen. It licks away the Parmesan Crust, the Upper Sauce
Layer, the Spinach Formation. On the southern flank of Dinosaur’s Split
Mountain Anticline, uplift and erosion have brought into view a
150-million-year-old riverbed strewn with the bones of ten different
species of Jurassic dinosaurs: Stegosaurus, Allosaurus, Camarasaurus,
Apato-saurus...the Hamburger Layer!
Earl Douglass, a
paleontologist in the employ of Pittsburgh’s Carnegie Museum, discovered
this site on a fossil-hunting expedition in 1909. A strand of eight
Apatosaurus tailbones first snagged his gaze. Excavations over the
ensuing decades unearthed hundreds of thousands of pounds of fossils,
laboriously extracted from the stone with hand pick and wedge and then
sledge-hauled out for shipment to Pittsburgh. Eventually the Carnegie
exhibit halls (and basement and closets) could hold no more, and
Douglass and his crew moved on. The famous quarry wall of Dinosaur
National Monument is the leftovers, but there is nothing catch as catch
can about it. More than 1,500 dinosaur bones remain in place. They have
been showcased through a painstaking process called reliefing—chipping
away surrounding rock—but are otherwise as prehistory left them.
It
was Douglass who had the idea to turn the fossil wall into a natural
museum. “How appropriate to build a fair sized building over them to
protect them,” he wrote in his low-key, anti-hyperbolic prose. “...To
have it large enough to contain related fossils and...explanatory
descriptions, pictures, paintings to represent scenes in the age in
which they lived.” The journal entry is dated October 29,
1915.Wholesale various Glass Mosaic Tiles from china glass mosaic
Tiles Suppliers. The Great Depression and institutional apathy got in
the way, but in 1958, that is what America came to have. The “fair
sized building” doesn’t just protect the bones; it comprises them. The
fossil-studded face serves as the building’s fourth wall.
Every
visitor’s first question is invariably the same: Why did so many
dinosaurs die here? The quarry wall holds bones from more than 400
individuals. The prevailing theory is that they didn’t, in fact, die
here; they died elsewhere and were carried to this spot on a raging
current. An epic drought caused a dinosaur die-off, and was followed,
the thinking goes, by an equally epic flood. Remains of these creatures
were swept into the cleft of the valley and borne along until the
floodwaters receded and the current slowed and they drifted to the
river bottom. Unfortunately for paleontologists, the bodies were by
this time no longer intact. They had come apart as they decomposed and
tumbled through the river. In many cases, scavengers may have torn away
limbs, so the bones of extremities landed far afield from their
torsos. The riverbed’s fossils are scattered and chaotic, toe bones
inside the curve of a rib, a Diplodocus leg bone beside a run of
Camptosaurus backbones. It’s as if a tornado touched down in a natural
history museum.
Staring at the fossil wall, you appreciate the
enormousness not just of the reptiles themselves, but of the
paleontologist’s challenge in reconstructing them. Whose (relatively)
small head is this? Did it belong to someone’s offspring, or is it a
different kind of beast altogether? A complete dinosaur skeleton
preserved as it fell is a rare thing, and far more often the
paleontologist confronts a jumbled mess like the one on display in
Dinosaur National Monument. Some prehistoric birds were especially
tricky for paleontologists, because distinctive features like skull
crests didn’t show up until maturity. “So the babies look like
different species,” says ranger Erin Cahill. “Excuse me.” She turns to
address a grade-schooler poised to scale a low section of wall. Her
voice drops an octave. “Get down, please!” (Visitors are encouraged to
touch the fossils, but not with the bottoms of their sneakers.)
It
is equally difficult, faced with a jigsaw puzzle of disarticulated
bones, to discern the subtleties of anatomy and the nuances of posture
and gait.We open source indoor tracking
system that was developed with the goal of providing at least
room-level accuracy. There’s no picture on the cover of the box. So the
scientists make their best guess and, like everything else, it
evolves. One of the Dinosaur National Monument brochures shows
paleontologists’ renderings of Stegosaurus over the years since its
discovery. In the earliest drawing,A Dessicant dry cabinet
is an enclosure with a supply of desiccant which maintains an
internal. the plates cover the creature’s back like scales, reflecting
the theory of the day: that they functioned as armor. A more recent
illustration shows the plates erect and angled apart from one another;
like the big upright ears of the desert fox, the plates may have served
to radiate heat and cool the beast.Our aim is to supply air purifier
which will best perform to the customer's individual requirements. The
thinking on T. rex has evolved as well. He has gone from Godzilla to
Road Runner, the lumbering upright posture replaced with a speedy
level-backed gait. As for Apatosaurus, he long ago left the swamp. The
theory that put him there—that without water to buoy him, his limbs
would be too weak to support his bulk—turned out to be false.
沒有留言:
張貼留言