Geoscience Reference
In-Depth Information
that formed the gorgeous cliffs behind the
puesto.
Looking for fossils
usually involves a lot more walking than it does digging. There are two
basic kinds of fossil collecting, prospecting and quarrying. When
one first begins searching for fossils in a new area, as we were, one
starts by prospecting. As the name implies, this involves walking
over promising-looking ridges, flats, and ravines while looking for
small fragments of fossil bone that are weathering out of the rock lay-
ers on the surface of the ground. These fragments are clues that a
dinosaur skeleton may be buried underneath the weathered surface of
the rock. A crucial skill is to be able to distinguish between the
ancient rock layers and younger layers or debris exposed on the surface.
Although the ancient rocks that entomb dinosaur skeletons are often
exposed in bare ridges and ravines, sometimes they are partially cov-
ered by much younger soils. So, inexperienced collectors frequently
spend hours searching in these younger soils only to find the bones of
a cow that died last winter—a very discouraging experience.
The color and mineral content of fossils varies from place to place,
depending on the chemical reactions that occurred as the bones and
teeth became petrified. When collecting in a new area, a good prac-
tice is for the first person who finds a fossil fragment to pass it around
so that other collectors can begin to develop an image of what to look
for. That's why we assembled the crew to examine the dinosaur eggs
immediately after we first discovered them. Finding fossils requires
patience and determination, and sites may yield their fossils only after
having been examined two or three times.
After finding fragments of fossil bone weathering on the surface, it
is critical to look for their source. Sometimes, one can follow a trail of
small fragments that have washed down a hillside right up to where
an entire dinosaur skeleton is buried beneath the surface. It's like a
detective following drops of blood to locate a body, and this approach
would lead us to some of our best finds. In other instances, whole
days can be spent prospecting for fossils without ever finding one
splint of bone, let alone a complete skeleton in the ground. While we
prospected this first day, we were serenaded by the screeches and
squawks of cliff-dwelling parrots that lived along the rocky ridges
around the
puesto.
If one is lucky enough to find fragments that lead to a good fossil,
it must be excavated and transported to a museum for final cleaning
