THE QUATERNARY GEOLOGY AND GEOMORPHOLOGY OF BIG BONE LICK STATE PARK, KENTUCKY

Big Bone Lick State Park is located in the Big Bone Creek valley in northern Kentucky, 2.75 miles northeast of its confluence with the Ohio River. The site has been internationally known for over 200 years for its wealth of late Pleistocene vertebrate fauna who were attracted to the site by abundant salt springs, a few of which are still active today. The park is rich with evidence for the complex glacial history of northern Kentucky. High-level fluvial deposits left by the ancestral Kentucky River prior to the incision of the Ohio River valley are found on the ridges. During the “Deep Stage” drainage reorganization, the Ohio River Valley and its tributaries including Big Bone Creek were incised into the Upper Ordovician bedrock, which forms the valley walls. During both the Illinoian and Wisconsin glaciations, tributaries were dammed up to form valley-bound lakes, leaving behind lacustrine terrace deposits. Incised into this terrace are two sets of alluvial terrace deposits, and the modern floodplain. While previous work has been done on the paleontology and geology of the park, there are still many questions regarding terrace development during and subsequent to the Wisconsin glaciation.

Detailed surveying has been performed to define the geometry and elevation of the terrace deposits, and five test borings were drilled to bedrock by the USGS. Comparison of the terrace remnants clearly defines the lacustrine terrace, inset with a sparsely preserved older alluvial terrace, and a younger alluvial terrace, within which the springs and fossils are found. A thin, generally gravelly layer between the alluvial deposits and the underlying lake deposits resulted from incision and aggradation following the Wisconsin glaciation. Grain size analysis and clay mineralogy of core samples reveal little difference between the generally silty clay of the lacustrine and alluvial sediments; pollen analysis and isotopic analysis reveal more detail about changing environmental conditions.

This project is part of a cooperative investigation by the USGS, Kentucky Geological Society, Northern Kentucky University, the University of Kentucky, and the University of Cincinnati. The maps, cross sections, and analysis will be used by park management, and will be part of a publication produced for the general public.