Sawmill Branch contains fossils from more than one formation and epoch, but everything I find online says C. catticus in Summerville come from the Chandler Bridge Formation (upper Oligocene).
ID references:
1. Gale, B. (2020). A Beachcomber's Guide to Fossils. The University of Georgia Press.
2. Rabi, M., & Botfalvai, G. (2008). A preliminary report on the Late Oligocene vertebrate fauna from Mariahalom, Hungary. Hantkeniana, 6, 177-185.
3. Godfrey et al. (2018). The Geology and Vertebrate Paleontology of Calvert Cliffs, Maryland, USA. Smithsonian Contributions to Paleobiology.
4. Maisch IV, H., Becker, M., & Chamberlain Jr, J. (2015). Chondrichthyans from a lag deposit between the Shark River Formation (Middle Eocene) and Kirkwood Formation (Early Miocene), Monmouth County, New Jersey. Paludicola, 10, 149-183.
ID and Chandler Bridge Formation reference:
1. Bourdon, J. (2004-2008). Genera from the Fossil Record: Carcharoides. Elasmo. http://www.elasmo.com/frameMe.html?file=heim/leecreek/lc-c_catticus.html&menu=bin/menu_topics-alt.html