Geology topics

Research about Tennessee, North Carolina

Source-linked reports with geographic coverage including Tennessee, North Carolina.

4 recordsLinked to original sources

USGS2020

Black bear movement and food conditioning in an exurban landscape

Conflicts between humans and wildlife have become increasingly important challenges for resource managers along the urban‐wildland interface. Food conditioning (i.e., reliance by an animal on anthropogenic foods) of American black bears (Ursus americanus ) is related to conflict behavior (i.e., being bold or aggressive toward humans, consuming human food or garbage, causing property damage) and often occurs in communities adjacent to Great Smoky Mountains National Park (GRSM or Park), USA. The goal of our study was to evaluate black bear space use in GRSM and in exurban areas on surrounding private lands and to identify factors associated with food conditioning and conflict behavior. We radio‐collared 53 bears (29 males, 24 females) from 2015 to 2017 to compare space use characteristics and used carbon isotopic signatures (δ13C) from bear hair to assess food conditioning. We then performed an integrated step selection function (iSSF) analysis to characterize and compare movement and resource use as related to food conditioning. Based on the stable isotope analyses, 24 bears were classified as food conditioned (FC; 16 males and 8 females) and 37 were not food conditioned (NFC; 14 males and 23 females). Annual 95% kernel density estimate (KDE) home ranges and 50% KDE core area estimates of female and male bears did not differ by level of food conditioning (i.e., mean δ13C), but 95% and 50% home ranges of FC females were smaller than NFC females when data from 2015, a year of food scarcity and abnormally large home ranges, were excluded. The mean proportion of exurban development (e.g., roads, buildings, openings) within 95% KDE and 50% KDE home ranges of females increased with mean δ13C (i.e., greater food conditioning). The iSSF models indicated that FC bears were more likely to use forest openings associated with higher levels of development than NFC bears. We used those models to demonstrate how landscape modifications can reduce bear use of exurban areas, particularly for NFC bears. Our stable isotope, movement, and resource use data indicate that conflict behaviors displayed by many bears within GRSM were learned in areas outside Park boundaries. © 2020 The Wildlife Society.

Tennessee, North Carolina↗

USGS2003

Temporally and spatially uniform rates of erosion in the southern Appalachian Great Smoky Mountains

We measured 10 Be in fluvial sediment samples ( n = 27) from eight Great Smoky Mountain drainages (1–330 km 2 ). Results suggest spatially homogeneous sediment generation (on the 10 4 –10 5 yr time scale and >100 km 2 spatial scale) at 73 ± 11 t km −2 yr −1 , equivalent to 27 ± 4 m/m.y. of bedrock erosion. This rate is consistent with rates derived from fission-track, long-term sediment budget, and sediment yield data, all of which indicate that the Great Smoky Mountains and the southern Appalachians eroded during the Mesozoic and Cenozoic at ∼30 m/m.y. In contrast, unroofing rates during the Paleozoic orogenic events that formed the Appalachian Mountains were higher (≥10 2 m/m.y.). Erosion rates decreased after termination of tectonically driven uplift, enabling the survival of this ancient mountain belt with its deep crustal root as an isostatically maintained feature in the contemporary landscape.

Tennessee, North Carolina↗

USGS2003

Erosion of an ancient mountain range, the Great Smoky Mountains, North Carolina and Tennessee

Analysis of 10 Be and 26 Al in bedrock (n=10), colluvium (n=5 including grain size splits), and alluvial sediments (n=59 including grain size splits), coupled with field observations and GIS analysis, suggest that erosion rates in the Great Smoky Mountains are controlled by subsurface bedrock erosion and diffusive slope processes. The results indicate rapid alluvial transport, minimal alluvial storage, and suggest that most of the cosmogenic nuclide inventory in sediments is accumulated while they are eroding from bedrock and traveling down hill slopes. Spatially homogeneous erosion rates of 25 - 30 mm Ky −1 are calculated throughout the Great Smoky Mountains using measured concentrations of cosmogenic 10 Be and 26 Al in quartz separated from alluvial sediment. 10 Be and 26 Al concentrations in sediments collected from headwater tributaries that have no upstream samples (n=18) are consistent with an average erosion rate of 28 ± 8 mm Ky −1 , similar to that of the outlet rivers (n=16, 24 ± 6 mm Ky −1 ), which carry most of the sediment out of the mountain range. Grain-size-specific analysis of 6 alluvial sediment samples shows higher nuclide concentrations in smaller grain sizes than in larger ones. The difference in concentrations arises from the large elevation distribution of the source of the smaller grains compared with the narrow and relatively low source elevation of the large grains. Large sandstone clasts disaggregate into sand-size grains rapidly during weathering and downslope transport; thus, only clasts from the lower parts of slopes reach the streams. 26 Al/ 10 Be ratios do not suggest significant burial periods for our samples. However, alluvial samples have lower 26 Al/ 10 Be ratios than bedrock and colluvial samples, a trend consistent with a longer integrated cosmic ray exposure history that includes periods of burial during down-slope transport. The results confirm some of the basic ideas embedded in Davis’ geographic cycle model, such as the reduction of relief through slope processes, and of Hack’s dynamic equilibrium model such as the similarity of erosion rates across different lithologies. Comparing cosmogenic nuclide data with other measured and calculated erosion rates for the Appalachians, we conclude that rates of erosion, integrated over varying time periods from decades to a hundred million years are similar, the result of equilibrium between erosion and isostatic uplift in the southern Appalachian Mountains.

Tennessee, North Carolina↗

USGS1958

Stratigraphy of ocoee series, Great Smoky Mountains, Tennessee and North Carolina

Much of the Great Smoky Mountains, which span the boundary between Tennessee and North Carolina, is formed of the Ocoee series, of later Precambrian age. This is a body of terrigenous clastic sedimentary rocks, which has minor intercalations of limestone and dolomite but no volcanic components or known fossils. The series is probably 30,000 feet or more thick. It lies unconformably on a basement of earlier Precambrian granitic and gneissic rocks, and on the northwest side of the mountains it is overlain by the Cochran formation, or basal unit of the Chilhowee group, which is of Cambrian and Precambrian(?) age. South of the mountains it is overlain by rocks of the Murphy marble belt; here, the top of the Ocoee is placed tentatively at the base of the Nantahala slate. The Ocoee series is divisible into three broad units of regional extent and contrasting lithologic character, which are herewith designated groups and named the Snowbird group, the Great Smoky group, and the Walden Creek group. The groups consist of local intergrading and intertonguing formations and have complex stratigraphic and structural relations. The Ocoee series is split by major thrust faults into three sequences, a southern, central, and northern, none of which contains more than two groups of the series. The lowest group, the Snowbird, is best developed in the central sequence where it is more than 13,000 feet thick; it is much thinner in the southern sequence. In both sequences it lies unconformably on granites and gneisses. Toward the east it is largely sandstone, but this is interbedded with and intertongues westward into finer-grained sandstone, siltstone, and argillaceous rocks. These differences permit the Snowbird group to be divided, in ascending order, into the Wading Branch formation, Longarm quartzite, Roaring Fork sandstone, and Pigeon siltstone. Toward the west the Snowbird is represented by more strongly metamorphosed rocks termed the Metcalf phyllite. Above the Snowbird group in the southern sequence is the Great Smoky group, more than 25,000 feet thick. The lower part, termed the Elkmont sandstone, is fine-grained sandstone. The middle part, termed the Thunderhead sandstone, is poorly sorted, coarse, feldspathic sandstone in graded beds. The upper part, termed the Anakeesta formation, includes many beds of dark argillaceous and silty rocks. South of the Great Smoky Mountains the Great Smoky group is overlain by the rocks of the Murphy marble belt. The Snowbird group in the central sequence is overlain in a few places by coarser-grained rocks. These somewhat resemble those of the Great Smoky group, but their stratigraphic relations to it are not demonstrable, so that they are left as unclassified parts of the Ocoee series. In one area such rocks are named the Rich Butt sandstone, in another the Cades sandstone. In the northern sequence the Walden Creek group, about 8000 feet thick, forms a varied assemblage of argillaceous and silty rocks and quartz-pebble conglomerate, with locally prominent quartzite, limestone, and dolomite. The Walden Creek group is divided, in ascending order, into the Licklog formation, Shields formation, Wilhite formation, and Sandsuck formation; the Wilhite is in turn divided into the Dixon Mountain member and Yellow Breeches member. The Walden Creek is overlain by the Chilhowee group of Cambrian and Precambrian(?) age but is in fault contact with the Snowbird group on the southeast; it is not in contact with the Great Smoky group. Northeast of the Great Smoky Mountains, the Walden Creek group is reported to overlie the Snowbird group as part of a sedimentary sequence from the basement rocks upward through the Chilhowee group into the overlying Paleozoic. © 1958, The Geological Society of America, Inc.

Tennessee, North Carolina↗