The first thing to know about the Coon Creek Formation in Tennessee is that the name has not always been Coon Creek. These strata in Tennessee were originally considered a “tongue,” or extension that pinched-out to the north, of the Ripley Formation. The Ripley Formation was named by E.W. Hilgard for exposers of the sediments near Ripley, Mississippi in 1860. The strata in Tennessee, best exposed along Coon Creek in McNairy County, were elevated to formation status by Mississippi State University stratigraphy Ernest Russell during his mapping of the region in the 1950s. The Tennessee strata is now referred to as the Coon Creek Formation and the exposures along Coon Creek, at the “Old Dave Weeks Place,” now the Coon Creek Science Center, became the type locality and type section for the deposit. In most of Mississippi and elsewhere, these strata are still referred to as Ripley.
The earliest record of fossils from what became the Coon Creek Formation was made by Tennessee’s first State Geologist, Gerard Troost, on October 24, 1833. Troost took a 29-day trip to West Tennessee that included the Cretaceous strata. While traveling between sites, Troost learned of a well being dug that had revealed numerous shells and decided to investigate the find. Troost mistakenly identified the fossils as very large individuals of the genus Gryphaea being collected out of a marl; however, the fossils Troost saw were more likely the large, coiled oyster Exogyra. The next day he was traveling in what was then Perry County and encountered more marl (Coon Creek Formation with Exogyra and another oyster, Ostrea).
As the 1800s wore on, several other prominent Tennessee geologists added to the knowledge of this deposit. The “green sand marl” is listed as the basal Cretaceous strata by Nelson Saylor “An Outline Geological Map of Tennessee”, published in 1866, based upon the work of several geologists listed below.
James Safford, Tennessee’s second State Geologist, described the “Green Sand or Shell Bed formation” from Hardin, McNairy, and Henderson counties in his “Geology of Tennessee” in 1869. Safford recognized the green coloring in the sand as coming from the abundant occurrence of the mineral glauconite, also noting that the mineral provided an excellent fertilizer for the area. Safford published a page-long list of the taxa he collected from the “marl” exposed at several localities, but his collection did not come from the location that would become the future type-section. His fossils were identified by prominent paleontologists Timothy Abbott Conrad and William More Gabb in another publication. Safford accurately described the formation saying, “it abounds in fossils” and that it “is pre-eminently the shell-bed of the Post-Paleozoic beds of West Tennessee.” The Cretaceous strata continued to be studied by stratigraphers seeking to trace these beds regionally for economic reasons. In 1899 State Geologist and Vanderbilt geologist L.C. Glenn published an extensive study of the outcropping Cretaceous strata in West Tennessee in which he summarized the distribution and quality of groundwater in the strata.
Early in the 20th century, Johns Hopkins University paleobotanist Edward W. Berry visited the region to study fossil plants from the Cretaceous and younger deposits and became acquainted with the exquisite shelly fossils. Berry would publish his palaeobotanical studies as a U.S. Geological Survey Professional Paper 136, The Flora of the Ripley Formation, in 1925. Berry contacted U.S.G.S. stratigrapher Lloyd W. Stephenson about the deposit and encouraged his study of Ripley in Tennessee. In an interesting bit of history, the U.S.G.S. workers were unable to conduct their work in Tennessee directly due to some friction between the agencies. Berry suggested that Stephenson recruit a graduate student to take-on the project of describing the extensive Cretaceous outcrop belt in West Tennessee and the abundant fauna of the Ripley Formation exposed at Coon Creek as a dissertation topic. That student was Trenton, Tennessee native and Vanderbilt University graduate Bruce Wade, who began his studies in 1915 and published his iconic monograph, U.S.G.S. Professional Paper137, The Fauna of the Ripley Formation on Coon Creek, Tennessee, in 1926.
The Coon Creek fossil deposit was on the property of West Tennessee farmer Dave Weeks. The history of the Weeks family has been nicely summarized in a McNairy County newspaper article from 1988 as told by Weeks’ grandson John D. Mills at about the same time frame that the Coon Creek Science Center was being obtained and constructed. According to Mills, the Weeks family purchased the 176 acres of land that Coon Creek ran through in 1867. At that time the site was “virgin forest” with the then unnamed Coon Creek being just a small drainage ditch with few fossils exposed. In 1888, Dave Weeks purchased the site from his mother along with an additional 75 acres. Weeks cleared the land of timber to start his farm. He deepened and widened the drainage by shovel to carry away rainwater from his bottomland. Within 20 years or so, erosion had deepened the drainage and began exposing the fossils that had laid buried for over 70 million years. Weeks would grind the fossilized shells into a meal that he could feed to his chickens, providing calcium to strengthen their eggs.
In 1915, Bruce Wade began his studies of the site, during which time the fossiliferous nature of the site became internationally recognized and it’s published location was “The Dave Weeks Place Coon Creek, Enville, TN”. Davie Weeks died in 1941. The Weeks family continued to live on the property until 1953 when they sold it to the A.Z. Smith family as a retirement property. The Smiths built the current house on the property in 1975.
With the scientific importance of the Coon Creek Formation and the type locality well established by the 1960s, researchers were visiting the Coon Creek Fossil Beds at the “Old Dave Weeks Place” regularly. The Smiths knew the importance of the site and kept it open to visitors, even putting “The Fossil Farm” on their mailbox. As early as 1921, staff from the Pink Palace Museum in Memphis would visit the site to collect fossils for the museum. By the early 1980s, the Smiths were ready to move and needed to find a way to preserve the property, so they approached numerous state agencies, including the University of Tennessee at Martin, to purchase the property and protect it. Unfortunately, these state agencies could not purchase the property, primarily because an actual monetary value of the fossils and the deposit could not be determined. The Pink Palace Museum’s private support group, Memphis Museums, Inc., was able to raise money to purchase the site in 1988. Immediately after the purchase, plans for a STEM camp were drawn-up and construction ensued. The Coon Creek Science Center opened its doors for educational outreach in 1989. The Museum did not have a research program of its own for the site but reached out to surrounding universities for assistance. Groups could schedule with the Museum for programing at the site by appointment. The site was owned and operated by the museum until 2019.
In the early 1990s, the Museum began a long-term association with the Geology program at the University of Tennessee at Martin to help with on-going research at the site, visiting university classes, and professional development for educators. The geology students at UT Martin spearheaded a drive to establish an Official State Fossil for Tennessee in 1997. After research candidates and polling of K-12 and university educators across Tennessee, the Coon Creek bivalve Pterotrigonia thoracica was identified as the winning candidate. In 1998, the Tennessee Legislature passed House Joint Resolution 552, sponsored by Senator Roy Herron and Representative Mark Maddox, as the Official State Fossil of Tennessee, making Tennessee the 38th state to designate a state fossil. In 2002, UT Martin chaired a special session of invited scientific papers presented at the Southeastern Section of the Geological Society of America annual meeting held in Memphis. This was also sponsored by the Southeastern Section of the Paleontological Society and the Southeastern Section of the National Association of Geoscience Teachers. There was also a field trip for professionals to visit the site. At this time, the site was recognized as a “lagerstätte deposit” (“motherload deposit”), which is generally considered the highest level of classification for fossil deposits, due to its abundance of pristinely preserved fossils and faithful recording of paleo-ecological conditions. UT Martin continued to oversee research projects on the site, with the Museum being the official repository for scientifically significant finds, until 2019 when the Museum turned-over all facilities and operations at the site to UT Martin as part of a 40-year lease agreement. Although the Museum retains ownership of the property all operations are controlled by UT Martin. The Covid-19 pandemic kept the facility closed to the public until 2020. During this time, UT Martin refurbished the facilities and added a Paleontology Lab and hiking trail to the existing complex and established a student internship program funded through the Kenneth V. Bordeau Paleontology Endowment in the Geosciences program at UT Martin. The fossil site re-opened to the public in 2021 with new programing by UT Martin staff and interns and a permanent on-site caretaker was hired. The UT Martin Coon Creek Science Center, directed by Dr. Michael A. Gibson, is operated out of the UT Martin Selmer Center, directed by Alan Youngerman.
Brister, R.C. 2016. Review of the discovery, research, and preservation of the Coon Creek type section locality: Bulletin of the Alabama Museum of Natural History, 33:5-19.
Brusatte, Stephen. 2003 (2nd printing). Stately fossils: A comprehensive look at the State Fossils and other official fossils: Fossil News, Boulder, CO, 234p.
Corgan, J.X. and M.A. Gibson. 1991. Early scientific exploration of West Tennessee: Gerard Troost's Travels in 1834: West Tennessee Historical Society Journal, 45:83-94.
Sohl, N.F. 1954, The gastropods of the Later Cretaceous Ripley, Owl Creek, and Prairie Bluff formations: Ph.D. Thesis, University of Illinois, Urbana, 536 p.
Wade, Bruce. 1926. The fauna of the Ripley Formation on Coon Creek, Tennessee: U. S. Geological Survey Professional Paper, 137:1-272.
Wingard, G.L. 2016. Review of Normal F. Sohl’s contributions to research at Coon Creek, Tennessee.
First, we must make the distinction between Coon Creek, which is the modern drainage creek that is eroding downward into the sediment layer preserving the fossils at the site, and the Coon Creek Formation, which is the over 70-million-year-old sea floor sediment that underlies the current topography of the outcrop belt and is the archive of geohistory during the time the sediments were initially deposited. The geologic process of erosion has exposed the ancient deposit that produces the agricultural soils of this region and, for those who learn how to decipher it, preserve the record of one phase in Tennessee’s ancient history; that history being the earliest history that one of the stars on the Tennessee flag represents – the Western Grand Division of Tennessee.
Why is the Coon Creek Science Center located in such a rural area? Why are geologists and paleontologists from around the world so excited about the site? Why is it so special that you can come to the site to collect fossils? Here we provide a very brief overview of the basic geology of the site and its importance to science and to society. Simply put, this site is the official reference site for all things related to the Coon Creek Formation, its fauna, and stratigraphic record. It is the home of Tennessee’s Official State Fossil, represents “dinosaur time” for Tennessee, and preserves some of the most complete and unaltered fossil organisms in the state. It attracts visiting scientists from across the United States and from around the world. It preserves a geohistorical record of the largest sea level stand in North American history. But unlike most sites of this prominence, it is also readily accessible to collectors and fossil enthusiasts as well as scientists. In fact, we encourage our visitors to participate in the scientific research as part of our “citizen science” outreach efforts. And therein lies the other reason for the importance of this geologic deposit and its fossils – education. Everything at the site is designed to be a learning experience by visitor participation. At the Coon Creek Science Center, visitors literally dig along-side paleontologists to reveal what has remained hidden for over 70 million years.
The Upper Cretaceous Coon Creek Formation preserves well over 400 species of fossils, including most major phyla of marine invertebrates, numerous varieties of fish and swimming reptiles, and even scattered plant remains. Geologist Bruce Wade established the “Old Dave Weeks Place” as the type-section for the “Coon Creek Tongue” of the Ripley Formation in 1926 and then the Coon Creek tongue was elevated to formational rank and mapped as such on the 1966 Geologic Map of Tennessee. In 1988, the site went under the protection of the Pink Palace Museum and the Coon Creek Science Center was built on the site. The late Harvard paleontologist Stephen J. Gould, commenting to Pink Palace Museum Director Doug Noble at the grand opening of the Coon Creek Science Center in 1989, called the “Old Dave Weeks” - Coon Creek Science Center site as one of the “twelve most important fossil sites in the United States”.
The Coon Creek Formation, originally considered a part of the Ripley Formation, is exposed in a north-south trending outcrop belt within the Mississippi Embayment in western Tennessee and eastern Mississippi that is traceable up to New Jersey (Figure 1). At the science center, the Coon Creek Formation is composed of gray to dark-green, micaceous, glauconitic quartz clayey-sand and is abundantly fossiliferous. The Coon Creek deposit represents the initial stages of a withdrawal of an extensive inland tropic sea that split North America into two landmasses: Appalachia to the east and Laramidia to the west. This inland sea, the Cretaceous Inland Sea was so high that the waters made a continuous connection from the current Gulf of Mexico to the Arctic Ocean. Rivers eroding Appalachia, which included Middle and East Tennessee to the mountains, Kentucky, Illinois, some of Missouri and Arkansas, deposited sand and clay into an embayment within this inland sea and quickly buried the teeming fauna living within its paleoenvironments.
The Coon Creek Formation has two parts as defined by sediment type that are separated by a zone of phosphatic concretions and iron-rich sandstone layers. The lower Coon Creek Formation is a massively bedded, glauconitic, fossiliferous blue to green clay sand and sandy clay that tends to weather brown. Only the lower Coon Creek lithofacies is exposed at the Coon Creek fossil site. The upper Coon Creek sediments consists of red iron-concretion beds interbedded with dark gray micaceous silty shale, which is usually referred to as the “ferruginous clay member”.
Bruce Wade designated the section at the CCSC (then the "Old Dave Week's Place") as the type locality for the Coon Creek tongue. Coon Creek is itself a young geomorphic feature of anthropogenic origin. Landowner Dave Weeks dug a drainage furrow for a field he had in cultivation after timber clearing. Within a mere 20 years, erosion had deepened the drainage to 5 meters. The cutbank of the creek exposes the fossiliferous strata and a floodplain to the west has developed within the valley. The floodplain contains channels with reworked ferruginous sandstone channel lags overlain by reworked Coon Creek sands and clays upon which the current soil horizons have formed. It was this flood plain that Dave Weeks (and surrounding farmers) farmed and across which you walk to reach the creek exposures when you visit the site. Similar channel and slope deposits occur in the upper portions of the cutbank exposures along the creek. Reworked Coon Creek fossils are often found in the flood plain deposits. The modern creek is actively transporting clay and sand reworked from the surrounding hillside. Iron cemented siltstone and sandstone, or “ferricrete” (cemented oxidized iron rocks) pebbles and cobbles, also make up a major component of the creek sediment. These clasts are often fossiliferous, especially with molds of peleycpods, gastropods, and preserving segments of crustaceans. Fragmented reworked and corroding fossil shells and teeth are also being transported.
Four distinct horizons can be visually delineated within the creek bed cuts, some of which represent weathering processes superimposed upon the original stratigraphy yet influenced by that stratigraphy so as to produce a distinct zonation visible on the outcrop surface (Figure 2). It demonstrates a complex combination of original stratigraphic characteristics and weathering enhancement, with zones accentuated by differences in shell preservation, grain size characteristics, and groundwater regime. Often particular zones can be delineated and correlated locally by the growth of moss and algae on the outcrop surface. The lowermost zone is unweathered, fossiliferous, dark gray, micaceous clayey sand, and sandy clay of the “classic” Coon Creek that most people will recognize. This zone is generally confined to the area near creek level and contains a higher moisture content in the sediment. This interval grades upward into an overlying fossiliferous, green-gray micaceous clayey sand and sandy clay. Often these two zones are gradational and indistinguishable from one another. Overlying these is an interval of tan, oxidized mottled clay and clayey sand that is extensively burrowed by now gone echinoids. Fossils appear leached from this horizon. Next is a weathered interval rich in molds and casts of invertebrates and iron cemented plates. This horizon appears to represent a highly leached and possibly condensed shell bed. The upper zones of the section are clay-rich and leached of fossil material. Rare bivalve and gastropod mollusk molds or “ghosts” appear on weathered surfaces. The uppermost reaches of this zone grade into the mottled and rooted modern soil horizons that develop on the Coon Creek sediments.
Taphonomy refers to the study of processes acting on a fossil deposit after final burial and up to collection by visitors and scientists. One distinctive feature of the Coon Creek fossil site is the lack of extensive compaction of the sediments nor recrystallization of the preserved fauna within the lower Coon Creek sediments exposed closest to creek level. Amazingly, the shells of fossils are unaltered and most of the ammonoid cephalopods still contain their iridescent “Mother of Pearl” nacre. It is this unaltered nature that makes the formation scientifically valuable enough to be classified as a “lagerstätte” deposit.