Smithsonian miscellaneous collections . streams. Each largeflood forms new channels of flow and destroys in part the work of itspredecessor. In such localities the measure of erosion or sedimentationis the algebraic sum of the erosion and deposition of successive floods. In several places a cross section of a much older channel is exposedin the wall of the arroyo. These exposures generally show a round-bot-tomed channel, filled with crossbedded sand to a depth of 2 to 10 feet,and the lenticular character of adjacent clay beds. Such channels areevidently interformational for they are shallow, o
Smithsonian miscellaneous collections . streams. Each largeflood forms new channels of flow and destroys in part the work of itspredecessor. In such localities the measure of erosion or sedimentationis the algebraic sum of the erosion and deposition of successive floods. In several places a cross section of a much older channel is exposedin the wall of the arroyo. These exposures generally show a round-bot-tomed channel, filled with crossbedded sand to a depth of 2 to 10 feet,and the lenticular character of adjacent clay beds. Such channels areevidently interformational for they are shallow, occur at all levels,and are covered by beds that are conformable with others, adjacentand contemporaneous. Evidently these channels are of the discontinu-ous type described on pages 13-14 and are to be distinguished fromthe relatively recent, buried channel discussed on pages 32-37. DEPTH OF THE ALLUVIUM Tangible evidence on the total depth of the valley fill is wanting inChaco Canyon. The well at the Societys Pueblo Bonito camp was dug.
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Keywords: ., bookcentury1800, bookdecade1860, bookidsmiths, booksubjectscience
