Denver Basin Project
The Denver Basin is a bowl-like geologic structure that
underlies the area between Boulder, Colorado Springs, and Limon.
The bedrock and sediments below the surface hold amazing plant and
animal fossils that lived at the end of the Cretaceous between 69
and 34 million years ago. The rocks that span this time period are
up to 3,000 feet thick and are exposed in road cuts, parks,
gullies, and construction sites all along the Front Range. In 2003,
a volunteer from the Denver Museum of Nature & Science
discovered a six-foot-long skull of a Triceratops dinosaur at a
housing development in Brighton.
The Museum's Dr. Kirk Johnson oversees the ongoing Denver Basin
Project to study the rocks, fossils, and groundwater in the basin,
along with Dr. Ian Miller and research associate Dr. Bob
Dr. Johnson's research focuses mainly on fossil plants. In 1994
when Steve Wallace, a paleontologist with the Colorado Department
of Transportation (CDOT), discovered a 64 million-year-old tropical
rain forest along Interstate 25 in Castle Rock, Dr. Johnson was
ecstatic. He calls it one of the Museum's most significant
"The Denver Basin contains tons of fossil leaves and pollen from
just the time period I like. My specialty time period is
between 60 and 70 million years ago, and the sediments in the basin
fall right in this time range. I didn't even realize this when I
moved to Denver, and then I got here and found that there were
fossils everywhere," Dr. Johnson said.
Many of the fossil leaves from Castle Rock are large, with
smooth margins and drip tips. After studying these leaves and their
similarities to modern rain forests, Dr. Johnson concluded that
Castle Rock once had more than 80 inches of rainfall and an average
annual temperature warmer than Miami. Essentially, the place where
Castle Rock now stands used to be a tropical rain forest.
Finds like these continue to happen in the Denver Basin, which
is why Dr. Johnson calls it "the no-brainer project." The National
Science Foundation funded this work from 1998 to 2008, but the
Museum continues to interact with CDOT, regional parks, and private
landowners to salvage fossils from natural outcrops and
construction sites as they are discovered.