Next time you you worry about earth shaking events picture this:
Archive for the ‘geology’ Category
SALT LAKE CITY (AP) — A newly discovered batch of well-preserved dinosaur bones, petrified trees and even freshwater clams in southeastern Utah could provide new clues about life in the region some 150 million years ago.
The Bureau of Land Management announced the find Monday, calling the quarry near Hanksville “a major dinosaur fossil discovery.”
An excavation revealed at least four sauropods, which are long-necked, long-tailed plant-eating dinosaurs, and two carnivorous ones, according to the bureau. It may have also uncovered an herbivorous stegosaurus.
Animal burrows and petrified tree trunks 6 feet in diameter were found nearby. The site doesn’t contain any new species but offers scientists the chance to learn more about the ecology of that time, said Scott Foss, a BLM paleontologist.
The fossilized dinosaurs are from the same late Jurassic period as those at Dinosaur National Monument, which straddles the Utah-Colorado state line, and the Cleveland-Lloyd quarry near Price.
It could be a decade or so before the full importance of the Hanksville quarry is known, Foss said. “It does have the potential to match the other major quarries in Utah,” he said.
The site, roughly 50 yards wide by 200 yards long, was excavated by a team from the Burpee Museum of Natural History in Rockford, Ill. Museum officials visited the site for about a week last summer and returned this year for a three-week excavation.
The area has long been known to locals and BLM officials as a dinosaur haven. But no one knew of the site’s magnitude until excavation began.
The bones were found in a sandstone channel of an ancient river.
“The preservation of these dinosaurs is excellent,” Foss said.
The mix of dinosaurs, trees and other species in the area may help scientists piece together what life was like 145 million years to 150 million years ago, including details about the ancient climate, Foss said.
BLM plans to close the site to conduct an environmental assessment for continued work in the area. The agency isn’t disclosing the exact location of the find because of security concerns.
Analyses of data gathered by Global Positioning System equipment atop one of Antarctica’s largest and most dynamic glaciers and by seismometers nearby suggest that friction in just one small area beneath the broad glacier regularly halts the ice’s lurching march to the sea.
Many of Antarctica’s largest ice streams — the megaglaciers that carry most of the ice draining off the continent — move at an irregular pace, first sticking in place, then surging ahead (SN: 3/31/07, p. 202). For instance, twice each day — at times related to the cycle of tides at the Antarctic coast — a large portion of the Whillans Ice Stream surges forward about 70 centimeters over the course of 25 minutes, says Matt King, a geophysicist at Newcastle University in England.
That may not sound impressive. But the total seismic energy triggered as this 200-kilometer-long, 100-kilometer-wide section of the ice stream scrapes across the underlying material is about the same as that of a magnitude-7 earthquake. Seismometers almost 1,000 kilometers away can detect the resulting ground motions, he notes.
Previous studies have suggested but not proved that surging glaciers can produce earthquakes (SN: 1/3/04, p. 14), because GPS data to record the movements of those glaciers wasn’t available. In this case, however, an array of GPS instruments atop the Whillans Ice Stream, each collecting data about 10 times each second, complemented the information gathered by seismometers in the region, he and his colleagues report in the June 5 Nature.
Each time the ice stream surged, its seaward motion began near a broad, low hump near the middle of its channel. Flow lines frozen into the ice suggest that the hump lies over a patch on the glacier bed where friction is significantly higher than under surrounding areas of the ice stream, the researchers say. And analyses of ice-penetrating radar images hint that this patch contains little if any subglacial water, which would tend to lubricate the ice stream’s flow. Together, the data indicate that the ice stream’s stick-slip behavior is largely controlled by friction in this one spot, roughly 10 kilometers wide. Resistance there prevents the glacier from flowing downhill until tidal and gravitational forces overcome the friction, the researchers speculate.
Whillans Ice Stream “is arguably the most unusual, dynamic, large glacier on Earth,” says Ted Scambos, a glaciologist at the National Snow and Ice Data Center in Boulder, Colo. The team’s research, he adds, “is a fascinating study … that shows how complex the Antarctic Ice Sheet is, and how even now we can be amazed by the interplay of some of the Earth’s most basic systems: oceans, ice and sediments.”
LUCKY SHOT A satellite image of a pyroclastic flow, an avalanche of hot ash and rocks that can travel at speeds of more than 100 kilometers per hour.
An image of a pyroclastic flow, one of the quickest and deadliest phenomena related to volcanic eruptions, has finally been caught by a satellite. These ground-hugging avalanches of hot ash and rocks can sweep down a volcano’s slopes at more than 100 kilometers per hour. They last no more than a few minutes, says Avijit Gupta, a geomorphologist at the University of Leeds in England. Luckily, he notes, the ground-gazing IKONOS satellite was passing over Indonesia’s Mount Merapi while it was erupting on June 16, 2006. Although scientists previously have tried to detect pyroclastic flows in satellite images, “normally the ash cloud over the volcano blocks the view,” he says. In this instance, strong winds blew the ash plume westward, revealing the flow, Gupta and his colleagues report in the May 27 Eos. The serendipitous image captured the pyroclastic flow when it was about 500 meters long, between 250 and 500 meters wide, and 50 meters high.