The geology of Hardin County, and the adjoining part of Pope County . ocalities, but not in Hardin County, where strata areinclined even more than 90° and are said to be overturned, but such conditions 32 GEOLOGY OF IIAKDIN COUNTY are associated with thrust faulting which is not the type of faulting exhibitedhere. The direction of the dip is said to be along the downward slope of thebeds. The term strike is applied to the line of intersection between a dippingrock surface and a horizontal plane (fig. 2). This line, then is always atright angles to the dip, and its direction is indicated by ref
The geology of Hardin County, and the adjoining part of Pope County . ocalities, but not in Hardin County, where strata areinclined even more than 90° and are said to be overturned, but such conditions 32 GEOLOGY OF IIAKDIN COUNTY are associated with thrust faulting which is not the type of faulting exhibitedhere. The direction of the dip is said to be along the downward slope of thebeds. The term strike is applied to the line of intersection between a dippingrock surface and a horizontal plane (fig. 2). This line, then is always atright angles to the dip, and its direction is indicated by reference to thecardinal points of the compass. In situations where the surface of dippingstrata is plane, the strike lines are straight, but if the dipping strata arewarped, the strike will be along curved lines. Observations upon the dip andstrike of rock formations are of great importance in working out the geologicstructure of a region. Upon the geologic map (PL I) an appropriate symbolis used to indicate dip and strike, a short, arrow-pointed line being directed. iv0 VV „: rfff Fig. 2.—Diagram illustrating the structural terms dip and strike. down the dip, and a longer line at right angles to the other being placed inthe direction of the strike. Topographic Development Contrary to the common conception of persons without geological ex-perience, the topography of a region, that is the irregularities of the surface,the hills, the valleys, the plains, are not unchangeable. The everlasting-hills are a myth, for every season brings about some changes, however most notable changes in topographic form are produced through theagencies of weathering, wind, and stream erosion. The rocks which areexposed at the surface or which are so situated that they come in contact withunderground waters, are constantly being subjected to changes of various GEOLOGICAL INTRODUCTION 33 sorts. Limestones are slightly soluble in ordinary ground waters. Thehard water of springs coming from
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectgeology, bookyear1920
