south-central Utah, the Grand Staircase-Escalante National Monument
preserves a geologic history spanning almost 275 million years. The
oldest rocks date from the Permian
Period, when the land that is
now Utah straddled the Equator. Some of the youngest rocks date from
Epoch, when crocodiles and palm
trees lived above the Arctic Circle. Many of the rock layers in the
national monument date to the time of the dinosaurs. In September 2010,
Scott Sampson of the Utah Museum of Natural History and his colleagues
new dinosaur species
this national monument.
On May 15, 2005, the Advanced
Land Imager (ALI)
on NASA’s Earth Observing-1 (EO-1)
satellite captured this natural-color image of part of the Kaiparowits
Basin. This central portion of Grand Staircase-Escalante preserves rock
layers primarily from the Mesozoic
Era. The branch-like shapes are
networks of canyons carved by rivers that dried up millions of years
ago. The area receives far less precipitation than it did in ages past.
The ridge running roughly
north-south through the scene is the Cockscomb, which is surrounded by
distinct rock formations deposited at different times in the geologic
past. West of the Cockscomb is the Navajo Sandstone, dating from the Triassic.
East of the Cockscomb are two formations from the Cretaceous:
the light-toned Wahweap and darker Kaiparowits.
The Kaiparowits Formation
the fossils discovered by Sampson’s team: Utahceratops gettyi
The newly discovered dinosaurs were both ceratopsians:
herbivorous animals characterized by big, flamboyant skulls.
In the late Cretaceous, when
ceratopsian dinosaurs lived, a shallow sea divided North America in
two. Geologists call the western
mini-continent Laramidia and the eastern mini-continent Appalachia. The
shallow sea advanced and retreated multiple times, and an asteroid
strike and other calamities about 65 million years ago brought the Age
of Reptiles to an end. Since that time, tectonic forces have uplifted
the area, leaving it largely high and dry as it remains today.
Fossils such as Utahceratops gettyi
richardsoni reveal a
fascinating history of life on Earth. October 13, 2010, marks the first
Fossil Day, a good time to dig
into the planet's history for Earth Science Week.