The science of remote sensing of the earth's surface with special cameras and other instruments that measure reflectance and/or emission of energy in the electromagnetic spectrum has had nearly exponential growth since the early 1940s. Since the mid-1950s scientists and engineers gradually have become aware of and interested in utilizing remote sensor technology in the natural sciences. This technology, developed principally from classified military projects, has been used only in unclassified civilian projects in natural sciences and earth resource fields during the past decade. Applications of remote sensing that have been advanced and tested include geologic use of Gemini and Apollo satellite photography, Nimbus AVCS (advanced vidicon camera system) and thermal infrare scanner data, as well as data from a number of aerial systems.

Remote sensor systems which have received attention in geology and allied disciplines are: (1) black and white (B/W) photography (panchromatic and infrared), (2) color and color infrared (IR) photography, (3) multiband (MB) photography, (4) thermal infrared (TIR) scanner images, (5) multispectral scanner (MSS) images (from near-ultraviolet to far-thermal infrared), (6) side-looking radar (SLAR or SLR) images, and (7) passive microwave scanner (PMS) images. Several of these systems have been tested from aircraft and spacecraft over parts of the Appalachians and adjacent regions. Remote sensing image data (ground observations, etc.) have provided useful information related to regional structures such as joint patterns, drainage patterns, fault traces, and rock types.

The application of geologic remote sensing is in its infancy, however, and these tests are not meant to imply that remote sensing is or will be a panacea for all the problems of Appalachian structural geology, but surely a combination of selected sensing systems can provide additional information for a well-balanced scientific approach to the problems of the Appalachians. Remote sensors provide synoptic views of large areas and of conditions that cannot be perceived either by the unaided eye or by field observations. These include surface distributions of heat, moisture, open water, and vegatative vigor differences, all of which are useful to the geologist.

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