As we begin 2026, we will be featuring the articles that make up Volume 55, which were published in May 2025. Enjoy these new additions to Southeastern Geology!
Click on the title of each work to view the full paper.
Critical Mineral Potential of Northeast Mississippi Sands
Allison I. Woolsey
Abstract:
Upper Cretaceous through Lower Eocene sand deposits in northeast Mississippi were sampled to understand their heavy mineral percentage and determine potential suitability for mining. Titanium minerals rutile, ilmenite, and their alteration product leucoxene were of interest, as well as zircon, monazite, and xenotime, which are sources of uranium (U), thorium (Th), and rare earth elements (REEs). Zircon is also a source of hafnium (Hf). These minerals have many uses and are important for manufacturing, engineering, and technological applications. Sampling and X-ray fluorescence (XRF) analysis of 202 sites indicated five sites with percentages of heavy minerals over 2.50% with abundant titanium minerals, Hf-containing zircon, U, Th, and indications of monazite. With the recent interest in domestic sources of critical minerals and REEs, characterizing these commodities within the ancient coastal deposits of Mississippi could establish the sampling area as an important and strategic resource.
Distribution of Natural Arches in Kentucky
Steven L. Martin and Stephen F. Greb
Abstract:
Natural arches are erosional features which are open on opposing sides. Kentucky has more than, 2,600 natural arches, which is the most natural arches in the eastern United States. Although there are many arches, there has been surprisingly little geologic research on Kentucky’s natural arches. Herein, 332 natural arches are examined relative to (1) the rock units in which they occur, (2) their position on the landscape, and (3) their position relative to local jointing. Comparison of 332 natural arches shows they occur in many different landscape positions, including on ridge tops, along cliff sides, along ridge sides, in stream valleys, and in sinkholes across the state. Ridge top and cliff sides are the most common positions (more than 80%). In Kentucky’s two coal fields, arches form dominantly in thick, cliff-forming, jointed sandstones. The largest concentration of natural arches in the state (more than 70%) occurs in the Lower Pennsylvanian, cliff-forming, Corbin Sandstone Member of the Grundy Formation, on the western margin of the Eastern Kentucky Coal Field in the Red River Gorge Geological Area. The longest span occurs in the Lower Pennsylvanian, cliff-forming, Caseyville Sandstone in the faulted, Fluorspar District of the Mississippian Plateaus physiographic region. In other areas, arches may occur in jointed sandstone or limestone. The largest clearances and widths of arches in the state occur in Mississippian limestones. Karst-associated arches occur in several limestone units in Ordovician and Mississippian strata in different parts of the state. Occluded and non-occluded arches occur in distinct parts of the landscape, often controlled by jointing. Span and joint orientations were measured from 262 natural arch locations. Lintels show a range of orientations, but 32% are parallel to sub-parallel (within 20°) to local jointing, and 26% are at right angles or oblique (70° to 110°) to joint orientations. Some regions show general trends of joint and arch orientations related to major faults or fault systems.
G. Robert Ganis, Ralph H. Willoughby, David J. Cicimurri, G. Richard Whittecar, and Steven J. Hageman
Abstract:
Beds interpreted as Eocene bolide-generated impact and tsunami deposits occur at Paint Hill in the Upper Atlantic Coastal Plain of Moore County, North Carolina,USA. These strata, herein named the Mount Helicon Formation, consist of four distinct beds comprising about one meter of total section. Bed 1 (the basal bed) is approximately 43 cm thick and consists of sandy carbonaceous clay with carbon glass and rock fragments and contains 14-18 parts per billion (ppb) iridium (interpreted as bolide impact ejecta). Bed 2 is approximately 9 cm thick and consists of non-cohesive silt-size particles and loosely bound sand-size accretionary lapilli-like masses composed of quartz and carbon glass particles imbedded in a gray-green, flakey clay matrix and contains 2-6 ppb iridium (interpreted as atmospheric fallout deposits). Bed 3, is a sandy-matrix breccia approximately 6 cm thick (although thickness is greater in some places because of large clasts). This bed has terrestrially-derived clasts such as paleosol rip-ups (gravel to boulder-size) and petrified wood logs, along with marine-derived clasts, such as fossiliferous chert fragments and (up to) meter-size clasts of rolled strata contains 1-2 ppb iridium (interpreted as tsunami-surge deposits). Bed 4 is approximately 15 cm thick and consists of medium to coarse quartz sand with occasional pea size quartz gravel (interpreted as a possible later tsunami deposit). The beds of the Mount Helicon Formation fill a channel cut into the upper part of newly described upper middle Eocene (Bartonian) siliciclastic strata, herein named the Paint Hill Formation. The Paint Hill Formation consists of approximately 11 m of clay, sandstone (some glauconitic), and conglomerate (interpreted as nearshore marine strata) that are divided into five intervals of fining-upward or coarsening-upward sediments comprising 2.5 high-resolution transgressive regressive cycles. The age of the Paint Hill Formation as determined from fossil shark teeth, specifically Pseudabdounia claibornensis, is Bartonian, 41.2-37.7 Ma, late middle Eocene. The uppermost unit in the Paint Hill Member has weathered to plinthic paleosol, indicating that the land area hosting these marine strata became subaerially emer gent, probably during the late Eocene. This emergent land provided a source for rip-up paleosol clasts found in Bed 3 of the Mount Helicon Formation. This discovery indicates that a catastrophic event (most likely the ~35 Ma Chesapeake Bay Impact that occurred about 380 km to the northeast of Paint Hill) generated bolide impact and tsunami deposits in a shallow marine and adjacent terrestrial setting in the southwestern part of the North Carolina Coastal Plain.