The most popular school program that the Stokes Nature Center offers is a geology lesson for second grade. I’m not sure what happens between second grade and adulthood to make our general perception of geology go from exciting to boring, but you would be amazed at how excited second graders get over rocks, and especially, over fossils.
Fossils are really quite rare – a very specific set of conditions have to be met in order to create one. Most living things decompose fairly rapidly upon death, leaving no trace of their existence behind. In order to create a fossil, this process of decomposition needs to be halted fairly rapidly, which typically means that the body is quickly covered by some kind of sediment – like sand, or soil or mud. For this reason, most fossils are found embedded in sedimentary rock. If pressure and moisture levels are just right, over the course of millions of years the organism’s molecules will slowly be replaced by minerals from the surrounding sediments – eventually turning bone into stone.
Only somewhere around one in a billion bones will make it through this process. From there the fossil has to remain intact and identifiable through eons of tectonic plate movement, earthquakes, and mountain uplift. Then, in order to be found it has to be located near enough to the earth’s surface, and in such a place where a human might come across it. Some geologists estimate that only 1 in 10,000 species that have ever lived have made it into the known fossil record, which makes me wonder what discoveries still await us.
Fortunately for us, prehistoric Utah was a place where fossilization happened with some regularity, as evidenced by places like Dinosaur National Monument and the Escalante Petrified Forest. Did you know that Utah has a state fossil? That distinction goes to the allosaurus, a predatory dinosaur that thrived during the Late Jurassic period. Numerous skeletons found in east-central Utah range in size from 10 – 40 feet in length, meaning this fearsome creature may have rivaled it’s more famous cousin Tyrannosaurus Rex for top predator status.
With such a rich fossil history, it’s not out of the question that you might stumble onto something truly amazing during a routine hike. Can you keep your find? Well, that depends on two things: the type of fossil, and whose land it was found on. On public lands in Utah, fossils of vertebrates cannot be collected, while fossils of invertebrates and plants can be. Private land owners have full rights to the fossils found on their property. With all fossils, it’s a great idea to report your find to the US Geological Survey so that your discovery can be documented for public or scientific research, display or education.
Fossil creation is an incredible phenomenon that has allowed us to glimpse the earth’s history in ways that would otherwise be completely hidden. Thanks to fossils, we can envision a prehistoric landscape filled with giant ferns, enormous dragonflies, long-necked allosauruses, and flying pterodactyls. Without the evidence in the fossil record, I doubt that even the most imaginative person among us could have envisioned such an amazing array of life.
For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.
Fossil Formation-Additional Reading:
State of Utah, Utah Geological Survey, Dinosaurs & Fossils (2011) https://geology.utah.gov/utahgeo/dinofossil/index.htm
McCalla, Carole and Eldredge, Sandy (2009) What should you do if you find a fossil? Utah Geological Survey. Accessible online at: https://geology.utah.gov/surveynotes/gladasked
Trefil, James (1996) 101 Things You Don’t Know About Science and Nobody Else Does Either. Houghton Mifflin Company: New York, NY, https://www.amazon.com/Things-Dont-About-Science-Either/dp/0395877407
Bryson, Bill (2003) A Short History of Nearly Everything. Broadway Books. New York, NY, https://www.amazon.com/Short-History-Nearly-Everything-Illustrated/dp/0307885151
Hylland, Rebecca, What are Igneous, Sedimentary & Metamorphic Rocks?, Glad You Asked, Utah Geological Survey, https://geology.utah.gov/map-pub/survey-notes/glad-you-asked/igneous-sedimentary-metamorphic-rocks/