Office of Geology Publishes 7.5 Minute Surface Geologic Quadrangle of Historic Tinsley Area
James Starnes, RPG & Jonathan Leard, GIT
The Office of Geology recently published a Surface Quadrangle map of the Tinsley area in Yazoo County with the help of the U.S. Geological Survey's Cooperative StateMap Grant Program. During this project Geology staff got a chance to study the important gravel resources in the area and to discover their deeper geologic significance helping to unlock the glacial history of the Pre-loess Terrace gravels and their place in the evolution of the Lower Mississippi River Valley. This map provides important scientific background that will help better understand the natural environment and help in the planning and stewardship of the area’s natural resources.
Geology staff have also been working in the Tinsley area with the conservation biology staff from the Mississippi Museum of Natural Science helping with fish sampling and natural habitat characterization to differentiate and propose two distinct separate races of the beautiful native Longear Sunfish (Lepomis megalotis). Additionally, a host of important Pleistocene age megafauna fossils such as Mastodon and ground sloth have come to our attention from local residents fossil collecting in the area. Important insight has also been gained regarding the geoarchaeological resources of the area that has shed light into the raw stone procurement once utilized by Native American inhabitants for lithic tool manufacturing.
The Tinsley area has had a significant impact on the state's history including Mississippi’s first oil boom. This was facilitated in part by one of our very own survey geologists, Fredric F. Mellen, while geologic mapping in Yazoo County in 1938. His observation of a seemingly out-of-place outcrop of the Moody’s Branch Formation near Tinsley led him to describe a geologic structure called a dome. He documented that the fossils' late Eocene age outcrop were structurally way too high compared to the surrounding geology. Geologists at the time were first learning that structures like this can typically associated with significant oil and gas deposits. The Tinsley oil and gas megafield became a state landmark as it was instrumental in helping the country in World War II. In addition, it has been a significant source of state tax revenue through the development of this oilfield which is still currently in operation. The official State Fossil, the fossil whale Zygorhiza kochii, was excavated from the Yazoo Clay in the Tinsley area with the help of the Mississippi Gem and Mineral Society. This amazingly complete fossil whale specimen can be found on display today, fully reconstructed, at the Mississippi Museum of Natural Science. As you can see, this area has had a significant impact on the state's history.