Driving the Gold Belt Byway: Indian Springs Trace Fossil Site and Phantom Canyon (Stops 19-21)
Our last major stop for the day on the Gold Belt Byway was Indian Springs Ranch, a ranch and campsite owned by the Thorson Family. The Indian Springs Trace Fossil Site is a National Natural Landmark (NNL) protected by the federal government, but it is owned by the Thorson Family and you must have permission and be accompanied by a family member to visit the site. Tours may be arranged by calling ahead.
Carly Thorson, who led our tour, is very knowledgable about the many plants of the ranch, as well as its history. The flower to the left is chinchweed (Pectis papposa), a lemony-scented plant with several medicinal uses. We also saw a petroglyph and some historical sites, including the cabin used by Wild Bill McKinney of Quantrill’s Raiders.
The Middle Ordovician (c. 450 million years old) trace fossils were found by Thorson’s father, Bennie C. Thorson, who worked the site for five field seasons with now-retired Colorado College professor William A. Fischer. The site was designated as an NNL in 1979. The voluntary NNL program, administered by the National Park Service, provides a way to recognize and protect important natural resources on any type of land, including private, local, municipal, state, and federal. Not all NNLs are open to the public, and many others require landowner permission to visit.
The Indian Springs Trace Fossil Site consists of a shallow excavation exposing a single bed of the Harding Sandstone, representing an “instant” in geologic time. The quarry is 16-18 feet above the base of the Harding. Much of the overlying sandstone has been eroded at this locality. The Thorsons keep the site covered to protect the exposed trace fossils, which remain in situ according to family policy.
Body fossils are rare in the Harding, including at Indian Springs, but trace fossils are abundant. Bony plates from ostracoderms (armored fish) and conodont elements are found there, but the site’s primary significance lies in its spectacular trace fossils from various animals moving across the Ordovician seafloor. At right, you can see a track left by a sea scorpion (eurypterid).
Ostracoderms were some of the earliest vertebrates. They lacked jaws, but were covered with bony plates, and were also the first organisms to use gills exclusively for respiration. Ostracoderms were bottom-feeders and probably relatively slow-moving. Here you can see a feeding trail of an ostracoderm. The close spacing of the feeding marks indicates that food was abundant on the Ordovician seafloor.
Tracks of several species of horseshoe crabs are quite common. The feeding traces typically curve either left or right according to the species. Horseshoe crabs are not actually crabs–they are more closely related to sea scorpions, and distantly related to the spiders–and they have evolved little since they first appeared in the fossil record. They are tolerant of harsh environments and protected by their sturdy shell.
This trace fossil shows an abruptly ended ostracoderm feeding trail, as the fish became a meal for a predator. The preservation of interactions like these is one reason the Indian Springs fossil site is so important. Other trace fossils at this site include tracks from trilobites, merostomes, and polychaete worms.
After Indian Springs, we drove back through Phantom Canyon (Stops 19-20), the location of several historical railroad sites, as well as more outcrops of Precambrian granodioriate and metamorphic schist and quartzite. We didn’t manage all of the stops on the Gold Belt Byway–that would take at least two days–but we had a great field trip.
-Melissa Barton
Photo Credits: Melissa Barton
Geologic Guidebook to the Gold Belt Byway, Colorado, by Thomas W. Henry, Emmett Evanoff, Daniel A. Grenard, Herbert W. Meyer, and David M. Vardiman (Gold Belt Tour Scenic and Historic Byway Association, 2004), is available at the Florissant Fossil Beds National Monument Visitor Center for $19.95 plus tax.
More Gold Belt Byway Posts:
- Stops 1, 2, 3, 5: Seasonal Training Field Trip (Florissant Area)
- Stops 4, 17, 18: Dome Rock and the Shelf Road
- Stops 12, 14, 15, 16: Garden Park and Skyline Drive Fossil Sites
i visited the florissant area in the mid to late 80’s and while exploring the area had the pleasure to meet a family that owned a ranch there. the owners son invited us to the ranch to meet his ailing father who had been very active in the fossil field and had made a lot of discoveries and had numerous fossils named for him or by him. i am planning on visiting this area again soon and would love to know the name of this family or how to get in touch with them again.the only other clues i might have were that the son’s father was very ill at the time and i believe that he had cancer. he treated us (complete strangers) as we were old friends and that is something you don’t run across to often and is not soon forgotten. larry shores-san antonio, texas
Comment by larry shores — September 9, 2007 @ 8:34 am
Hi Larry,
My sister-in-law is one of the Thorson’s that run Indian Springs. The father died in 1988 so the children are now running the ranch.
The phone # is 719-372-3907.
Beautiful area around there, I was there in 2003 & need to get back too.
Allyson
Comment by Allyson Onyshczak — April 28, 2008 @ 8:34 am
Thanks for the information. I am planning to go back up there this summer with some of my grad school classmates.
-MB
Comment by The Friends of the Florissant Fossil Beds, Inc. — May 3, 2008 @ 6:58 pm
Hi. I really enjoyed it. Help me! Please help find sites for: Wall clock. I found only this - http://turbo-tax.biz/. Browse our blog for helpful seo, search engine. Specializing in small business seo services. With best wishes :cool:, Lazar from Iran.
Comment by Lazar — May 20, 2009 @ 3:28 pm