The fertile Vega of Granada and the great plain of Guadix lie respectively off the western and northern flanks of the Sierra Nevada and are separated from each other by the much lower Sierra Harana. Level almost as a floor, on their borders their surfaces incline valleyward at low angles, producing a topographic feature most common in Spain—the filled valley out of which steep mountain ranges rise abruptly. The material with which these valleys are filled merits a fuller consideration than is here possible, but a record of somewhat hurried observations, with conclusions drawn therefrom, may be of value, since they apply to a region which has received but little attention from geologists. Von Drasche, who visited the province more than a quarter of a century ago, has furnished the best description of the deposits, a portion of which he has relegated to three formations, namely, the Alhambra conglomerate, . . .