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Earle Rupert Cressman

Publications and source records attributed to Earle Rupert Cressman.

At least 19 recordsLinked to original sources
USGS1981

Geologic mapping of Kentucky: A history and evaluation of the Kentucky Geological Survey--U.S. Geological Survey Mapping Program, 1960-1978

In 1960, the U.S. Geological Survey and the Kentucky Geological Survey began a program to map the State geologically at a scale of 1:24,000 and to publish the maps as 707 U.S. Geological Survey Geologic Quadrangle Maps. Fieldwork was completed by the spring of 1977, and all maps were published by December 1978. Geologic mapping of the State was proposed by the Kentucky Society of Professional Engineers in 1959. Wallace W. Hagan, Director and State Geologist of the Kentucky Geological Survey, and Preston McGrain, Assistant State Geologist, promoted support for the proposal among organizations such as Chambers of Commerce, industrial associations, professional societies, and among members of the State government. It was also arranged for the U.S. Geological Survey to supply mapping personnel and to publish the maps; the cost would be shared equally by the two organizations. Members of the U.S. Geological Survey assigned to the program were organized as the Branch of Kentucky Geology. Branch headquarters, including an editorial staff, was at Lexington, Ky., but actual mapping was conducted from 18 field offices distributed throughout the State. The Publications Division of the U.S. Geological Survey established a cartographic office at Lexington to prepare the maps for publication. About 260 people, including more than 200 professionals, were assigned to the Branch of Kentucky Geology by the U.S. Geological Survey at one time or another. The most geologists assigned any one year was 61. To complete the mapping and ancillary studies, 661 professional man-years were required, compared with an original estimate of 600 man-years. A wide variety of field methods were used, but most geologists relied on the surveying altimeter to obtain elevations. Surface data were supplemented by drill-hole records, and several dozen shallow diamond-drill holes were drilled to aid the mapping. Geologists generally scribed their own maps, with a consequent saving of publication costs. Paleontologists and stratigraphers of the U.S. Geological Survey cooperated closely with the program. Paleontologic studies were concentrated in the Ordovician of central Kentucky, the Pennsylvanian of eastern and western Kentucky, and the Mesozoic and Cenozoic of westernmost Kentucky. In addition to financial support, the Kentucky Geological Survey provided economic data, stratigraphic support, and drillhole records to the field offices. Geologists of the State Survey made subsurface structural interpretations, constructed bedrock topography maps, and mapped several quadrangles. Some of the problems encountered were the inadequacy of much of the existing stratigraphic nomenclature, the uneven quality of some of the mapping, and the effects of relative isolation on the professional development of some of the geologists. The program cost a total of $20,927,500. In terms of 1960 dollars, it cost $16,035,000; this compares with an original estimate of $12,000,000. Although it is difficult to place a monetary value on the geologic mapping, the program has contributed to newly discovered mineral wealth, jobs, and money saved by government and industry. The maps are used widely in the exploration for coal, oil and gas, fluorspar, limestone, and clay. The maps are also used in planning highways and locations of dams, in evaluating foundation and excavation conditions, in preparing environmental impact statements, and in land-use planning.

Kentucky↗
USGS1981

Surface geology of the Jeptha Knob cryptoexplosion structure, Shelby County, Kentucky

The Jeptha Knob crytoexplosion structure, described by Bucher in 1925, was remapped in 1973 as part of the U.S. Geological Survey and the Kentucky Geological Survey cooperative mapping program. The knob is in the western part of the Blue Grass region. Hilltops in the rolling farmland adjacent to the knob are underlain by the nearly flat-lying Grant Lake and Callaway Creek Limestones of middle Late Ordovician age, and the valleys are cut in interbedded limestone and shale of the Clays Ferry Formation of late Middle and early Late Ordovician age. Precambrian basement is estimated to be 4,000 ft below the surface. The mapped area is 50 miles west of the crest of the Cincinnati arch; the regional dip is westward 16 ft per mile. The 38th parallel lineament is 50 miles to the south. The structure, about 14,000 ft in diameter, consists of a central area 6,300 ft in diameter of uplifted Clays Ferry Formation surrounded by a belt of annular faults that are divided into segments by radial faults. The grass structure of the Clays Ferry Formation is that of a broad dame, but same evidence indicates that, in detail, the beds are complexly folded. The limestone of the Clays Ferry is brecciated and infiltrated by limonite. The brecciation is confined to single beds, and there is no mixing of fragments from different beds. A small plug of the Logana Member of the Lexington Limestone (Middle Ordovician) has been upfaulted at least 700 ft and emplaced within the Clays Ferry. The central uplift is separated by high-angle and, in places, reverse faults from the belt of annular faulting. The concentric faults in the zone of annular faults are extensional, and the general aspect is of collapse and inward movement. Lenses of breccia are present along many of the concentric faults, but not along the radial faults. At least same of the breccia was injected from below. The youngest beds involved in the faulting are in the Bardstown Member of the Drakes Formation of late Late Ordovician age. The faulted and brecciated beds are overlain by nearly horizontal dolomite and shale of Early and Middle Silurian age. The basal 5 ft of the oldest Silurian unit, the Brassfield Formation, contains calcarenite and calcirudite composed, in large part, of locally derived fragments from the Upper Ordovician formations. The Jeptha Knob structure was formed in latest Late Ordovician or earliest Early Silurian time. At the time of formation, the area was either very slightly above or very slightly below sea level; the sediments were already largely indurated. At the onset of Silurian deposition, the area of the central uplift was probably a broad shallow depression not more than about 15 ft deep, possibly surrounded by a rim of Upper Ordovician rocks or rock fragments. The origin of the Jeptha Knob structure cannot be determined from the available data. Shatter cones and coesite, considered by many to be definitive criteria far origin by impact, have not been found. On the other hand, geophysical studies indicate that there is no coincident uplift of the basement, and there is no certain relation of Jeptha Knob to any obvious structural trend.

Professional Paper↗
USGS1978

Geologic names of Ordovician rock-stratigraphic units exposed in Kentucky

This report summarizes and indexes the current usage of geologic names of exposed rock-stratigraphic units of Ordovician age in Kentucky. The Ordovician rocks crop out mainly in two separate areas in Kentucky (fig. 1). The larger area of outcrop, covering much of the middle part of the state, forms the major part of the Blue Grass region of Kentucky. Outcrops of this region are contiguous with outcrops of Ordovician rocks in southwestern Ohio and southeastern Indiana. The smaller area of fairly continuous outcrops of Ordovician rocks lies south of the Blue Grass region along the Cumberland River and its tributaries. These outcrops are contiguous with outcrops of Ordovician rocks in Tennessee. A few isolated exposures of Ordovician rocks lie outside the areas of continuous outcrop.

Kentucky↗