. Annual report of the Regents. New York State Museum; Science. NIAGARA FALLS AND VICINITY 41 of the cuesta, and ultimately prolong-ed these gullies into gorges, and carried the drainage into the subsequent streams. Streams of this type, which have their representatives in all coastal plain regions, have been called obsequent streams,^ their direction of flow being opposite to that of the consequent streams. The following diagram (fig. 4) illustrates this type of a stream and its relation to the subsequent and consequent streams. To this type of stream belongs the ancient St Davids gorge, as w
. Annual report of the Regents. New York State Museum; Science. NIAGARA FALLS AND VICINITY 41 of the cuesta, and ultimately prolong-ed these gullies into gorges, and carried the drainage into the subsequent streams. Streams of this type, which have their representatives in all coastal plain regions, have been called obsequent streams,^ their direction of flow being opposite to that of the consequent streams. The following diagram (fig. 4) illustrates this type of a stream and its relation to the subsequent and consequent streams. To this type of stream belongs the ancient St Davids gorge, as will be shown more fully in subse- quent Fig. 4 Diagram of a portion of a dissected coastal plain, showing old-land on the left, and two euestas with their accompanying inner lowlands. Three consequent streams have breached the cuestas, and subsequent streams from the lowlands join them. An obsequent stream is shown in the center of the outer cuesta. If we assume that during the greater part of the Mesozoic era, the land in this region remained in a constant relation tO' the sea- level, it becomes apparent that the southward retreating infaces of the cuestas formed by the resistant members of the Paleozoic rocks, became lower and lower, as the southward inclination of the strata carried the resistant beds nearer and nearer to sealevel. Eventually the escarpment character of the infaces must have become obsolete, from the disappearance, beneath the erosion level, of the weaker lower strata, which permitted the undermining of the capping beds. When this occurred, the capping strata alone contiruued ex- posed to the action of the atmosphere, and, from a cliff char- acter, their exposed ends were planed ofif to a wedge shape, thin- 'W. M. Davis. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original New York Sta
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Keywords: ., bookauthorne, bookcentury1800, bookdecade1880, booksubjectscience
