USGS · 70012345
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C.M. Nelson. 2018-02-13. Facies in stratigraphy: From 'terrains' to 'terranes'.. https://doi.org/10.5408/0022-1368-33.3.175
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Two North American contributions to the Global Geoscience Transects Program, the Quebec-Maine-Gulf of Maine transect and the Great Lakes portion of the United States-Canadian Border transect, are among the first to produce digital geology in a form that can be combined with gridded gravity and aeromagnetic data. Maps of shaded relief and color-composite bandpass-filtered potential-field data combined with overlays of digitized geologic contacts and faults reveal significant new geologic information, including the relative thickness of plutons, the structure of poorly exposed or concealed magnetic units, and possible evidence for mineralized ground. Mechanisms for capturing digital geology by use of scanners, commercial geographic information systems (GIS) software packages, and public-domain PC-based software packages are illustrated by examples from these two transects. The digital geology is combined with the potential field data by use of in-house raster-based image-processing software and commercial hardware. Geologic cross sections constructed along the transects may be tested and refined by using 2-D and 2.5-D magnetic- and gravity-modeling software. The integrated data sets ultimately allow construction of 3-D models of the crust within the transects.
The statement that a new era in exploration is opening will almost surely bring to mind the venturing of man into space and the ever more imminent exploration of the moon. The reference here, however, is to exploration of earth itself and to the unique capabilities for study of the earth that space technology will provide. Demands for water, minerals, energy, food, and for working, living and recreational space are outrunning our ability to meet them by traditional methods. In order to satisfy these demands, it is necessary now, just as it has been in the past, to look to the activities, the instruments, and the technologies that in part create the pressures for aid in meeting them. Studies being made at the U.S. Geological Survey and elsewhere of the potential applications of remote sensors in space to earth resources research indicate that now, at last, it will be possible to approach solutions on a regional or global basis. This paper discusses the plans for an Earth Resources Observational Satellites Program which will be designed for that purpose.