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Jarvis B. Hadley

Publications and source records attributed to Jarvis B. Hadley.

8 recordsLinked to original sources
USGS1974

Seismotectonic map of the Eastern United States

The purpose of a seismotectonic map is to describe the distribution of historic seismic activity in relation to geologic structures and tectonic provinces and to identify structures or regions that are characterized by consistent relations between seismic activity and structural features. An experimental study to test the feasibility of preparing such a map and its usefulness in evaluating earthquake hazards was initiated jointly by the U.S. Geological Survey and the former Seismology Division of the National Oceanic and Atmospheric Administration; financial support was provided by the U.S. Atomic Energy Commission. It was hoped that the study would develop evidence for the existence of tectonic regions or structural provinces that are useful in defining parameters of seismic hazard in relation to engineered structures. As with many experiments, this one did not produce the results envisioned at the outset, but it did result, we think, in assembling seismic and structural data useful in evaluating the distribution and origin of earthquakes in the eastern part of the United States and in delimiting areas of relative seismic activity.

Miscellaneous Field Studies Map↗
USGS1968

Geology of the Great Smoky Mountains National Park, Tennessee and North Carolina

The boundary between Tennessee and North Carolina is delimited for about 50 miles in midlength by the crests of the Great Smoky Mountains, which include some of the highest summits in the southeastern United States, and which culminate in Clingmans Dome (alt 6,642 ft). Ramifying spurs and foothills descend northwestward from the State line divide toward the Appalachian Valley in Tennessee, as well as southeastward toward the less regularly disposed mountains of the main part of the Blue Ridge in North Carolina. All the Great Smoky Mountains are heavily forested, the higher summits being covered by spruce and fir, and the lower slopes, by a great variety of hardwoods. Much of this forested mountain wilderness has been set aside for public benefit and enjoyment as Great Smoky Mountains National Park. For most visitors to Great Smoky Mountains National Park, prime attractions are its noble forests, its open coves set gemlike amongst them, the animals of the forests and coves, and the relics of the mountaineers who have made their homes there. Only now and then, when the visitor's trail through the forest must circuit a rough ledge of rock, can he realize that the forest and the soil on which it grows are a mere veneer—a thin cover over the ancient rocks of the mountains. In the Yosemite, the Grand Canyon, and most of our other national parks in the West, the situation is very different; there, the impact of the bedrock of the parks is overwhelming in relation to the plants and animals that live on the bedrock. The terrain of the Great Smoky Mountains, their soils, unconsolidated deposits, and details of slope sculpture tell a geologic story of the last few million years of earth history, a story dominated by the drastic fluctuations of the ice-age climate. Although the mountains themselves were not covered with glacial ice, the climate at this latitude approached glacial conditions, and the mountaintops were occasionally above tree line. Deposits of debris that resulted from the associated accelerated erosion of the hillsides during glacial intervals and the deeply weathered soils produced during the episodes of warm and humid interglacial climate are evident at many places. These climatic oscillations also controlled the flora and fauna. The complex process of adjustment of plants and animals to the prevailing climate is one of the factors that has produced their present great diversity. This latest phase of the geologic history is not further treated in this publication. Maps showing the younger deposits and interpretations based on them are included in the several recent U.S. Geological Survey Professional Papers referred to below. Our concern in this text and its accompanying map (pl. 1) is with the bedrock geology of the Great Smoky Mountains and their surroundings, and with the story of far earlier times in earth history—when there were no Great Smoky Mountains, and when the geography and the landscape were very different from those today. Because of the forest cover and the scantiness of rock outcrops, the bedrock geology of the Great Smoky Mountains is not easy to decipher, and this difficulty is compounded by the enigmatic nature of most of the rocks themselves. It thus has come about that knowledge of the geology of the mountains has lagged behind that in surrounding regions. Following pioneer investigations of Safford (1869) and of Keith (1895, 1896), little further geologic study of the mountains was made until after World War II. The present text and map summarize the results of the more recent investigations, details of which are given at much greater length in a set of U.S. Geological Survey Professional Papers (Hamilton, 1961; Hadley and Goldsmith, 1963; King, 1964; Neuman and Nelson, 1965).

North Carolina, Tennessee↗