As undergraduates in science, we search for opportunities to do research outside the classroom. But often classes can offer unique scientific experiences. From March 30 to April 2, my geobiology class took a field trip to Denver, Colorado.
At 1AM, we left by bus for Newark, New Jersey, and then flew to Denver. From the first moment, Denver International Airport established the atmosphere for the trip, with the presence of fossils even in the floors.
We began our first day with a visit to Red Rocks Park and Amphitheatre, where people can enjoy both music and scenery.
The rocks here are of the 300 million-year-old Fountain Formation. Between the Fountain Formation and the rocks below it is an unconformity, a buried erosion surface equivalent to a gap in the rock record and thus a gap in time. As the rocks below the Fountain Formation are 1.7 billion years old, 1.4 billion years are missing. The time of the uplift of the Ancestral Rockies was 300 million years ago, and much of the sediment was stripped and eroded as a result.
The placard above has marked the unconformity, to the left of which is the Fountain Formation. You can see that the rocks on the two sides are different.
Looking down from the top of the amphitheatre, we see Denver near the horizon, and closer is Dinosaur Ridge, our next major stop. We hiked Dinosaur Ridge, stopping occasionally to discuss the geology.
A volcanic ash layer was preserved in the sediments above. While fossils provide relative dating, ash layers allow for radiometric dating for specific numbers.
Part of Dinosaur Ridge preserves the footprints of dinosaurs. The Main Trackway Site, or "Dinosaur Freeway," is the ground on which the herbivore Iguanadon and some of its predators walked. Studying the footprints can tell us about predator-prey ratios and give size estimates for the dinosaurs.
Our last stop for the day was to the Denver Museum of Nature and Science. The vice president, Kirk Johnson, a friend of our professor, Peter Wilf, gave us a behind-the-scenes tour and told us about the snowmastadon project. The project started when a bulldozer ran into a mammoth skeleton in the village of Snowmass, Colorado. It turned out that thousands of bones of Ice Age animals lie in that area.
View of Denver from the museum:
Dr. Johnson summarized that the purpose of museums is to make discoveries, restore and preserve them, and tell the story. Just as he was talking about the public's interaction with the exhibits, a few kids were howling at the wolves in a diorama. Whatever buried interest I had for museums as a child is surfacing now, as I learned more about the active research done at museums and how direct the outreach is.
Cabinets of stored leaf fossils:
The above is a leaf fossil from the Castle Rock rainforest, a forest in Denver 64.1 million years ago, almost two million years after the end-Cretaceous mass extinction. While other forests of its time had low diversity as ecosystems recovered from the mass extinction, this forest had unusually high species richness. The sizes of leaves can be correlated with rainfall at the time, and paleobotanists (Kirk Johnson was one of them!) have found that the rainfall at Castle Rock rainforest was 2 meters a year. The mean annual temperature was between 20 and 22 degrees Celsius (around 70 degrees Fahrenheit). The Denver today is nowhere near so warm, and the annual rainfall is around 14 inches.
The Castle Rock rainforest is named for the fact that it was found near Castle Rock, where we visited on our second day.
Zoomed in on rainforest fossil site (which is now sealed off) from the top of Castle Rock:
Climbing the actual Castle Rock:
We then visited West Bijou Creek to check out an outcrop where the K-T boundary was exposed. The outcrop was found in an area of 9000 acres because the location of the bounary (at 993 feet) from a drilled core 2300 feet long was known, and an estimation of where the boundary would crop out was done with subsurface modeling. Dr. Ian Miller, curator at the Denver Museum of Nature and Science, another paleobotanist, accompanied us to the site.
The K-T boundary was about 40cm below the rod, and we still had to dig:
We later went to look for plant fossils not far from the K-T section:
A field book provides the orange background. During the field trip, we took notes and drew sketches in our field notes, recording down information so that later when we return to the notes, we can remember the details. This aspect reminded me of doing the documentation for research.
The third day ended our streak of nice weather. We headed to Colorado Springs for stops such as Garden of the Gods and Florissant Fossil Beds National Monument.
The above features my class at the Pierre Shale outcrop on Uinta Street. Much like Red Hill, the site was right next to the road but it was much steeper. The Pierre Shale formed from marine deposits around 85 million years ago.
We saw another unconformity, a clean contrast representing 500 million years of missing time:
In the cold, we toured Florissant Fossil Beds National Monument, established in 1969 when the area was to be subdivided for housing. The matter went to court in order to preserve all that was there. 1700 different species of plants and insects were discovered here, and it is home to magnificent petrified wood.
We are now almost twenty million years past the K-T boundary.
We ended our third day at Garden of the Gods:
The jagged appearance reminds me of China's Mt. Huang:
On our last day, we headed back to Denver Museum of Nature and Science while it snowed outside.
Prehistoric Journey, one of our textbooks, was co-written by Kirk Johnson. It goes along with the Prehistoric Journey exhibition at the museum, which displays ancient landscapes recreated using only the fossils found at the site.
This part of the exhibition shows life in the reefs of the Silurian period over 400 million years ago.
In our free time, I checked out many of the other exhibits, wandering through the crowds of elementary school kids on their own field trips. Without a doubt, Space Odyssey was an exhibit I had to go to. A friend and I went to the planetarium and saw Cosmic Journeys: A Solar System Adventure. The focus was on the presence of life in the solar system, going from planet to planet, examining the conditions of each. Habitability is a central topic in the field of exoplanets. It's quite shaking to think that we only began to wonder about life elsewhere what seems like seconds ago in Earth's long history and not even that long ago in the time of humans. The people of the past never had a reason to question or guess these possibilities; this curiously is almost like luxury, and I'm glad we're able to have that and share it with those like the kids who also sat in the planetarium, excited.