Observations Bearing on the Development of Meanders in Intermittent Streams

Modford and Ashland owo not a small part of thoir well-being to the entertainment of tourists. Tho surrounding mountainous topography and resulting inaccessibility has exercisod a highly soloctivo force in molding the ecological pattern of tho occupants. It has brought about a high degree of social selectivity and integration. It has meant that if the valley is to be a supply center for any class of economic goods such goods must bo of a concentrated and valuable type in ordor to compote with more favorably located districts. That the inhabitants of tho valloy have adjusted wisely is evidenced by the cultural landscape . As ono drives through tho valley an air of prosperity seems to prevail. Woll-paintod homes, urban or rural, beautiful lawns, shrubs and shado troes, good roads, well-groomed orchards, truck gardons , and fine livestock greet tho eye, and indieato a substantial regional wealth. It seems ovidont that the Roguo River valloy possesses sufficient regional re sources to onablo it to bo known as a center from which a distinctive culture omanatos, and a region oqual to few others as a delightful placo in which to live. Observations Bearing on the Development of Meanders in Intermittent Streams JOHN LEIGHLY University of California, Berkeley The paper dealt with arroyos cut in valley fills in northwestern New Mexico. These channels are now, produced during the past few decades by accelerated runoff resulting from overgrazing. Though new, they gonorally havo sinuous courses, in which typical meander forms are frequent . Detailed maps of selected sections of stream courses were displayed as lantern slides, which show the development of sinuosities from accidentally located depressions excavated by the streams flowing in tho older smooth-bottomed valleys. Through hoadward extension of these originally discrete depressions, tho sinuosities of the arroyos are produced. Tho meander forms result from sideward cutting in irregular bends, which gradually take on smooth curves. Examination of tho true meander forme leads to an inquiry into tho typical shape of a meander. Measurements made of the change in rhdius of curvature along tht sinuosities of the arroyos mapped indicates that tho doveloped meander through most of its length approaches tho form of a logarithmic spiral, rather than tho arc of a circle, ns has been supposod. (25) ...