Santa Clara Valley extends southeastward from San Francisco, lying between the Diablo Range on the northeast and the Santa Cruz and Gabilan ranges on the southwest. (See Pl. I.) Its north end is occupied by the southern part of San Francisco Bay. Toward the south it rises gradually and becomes increasingly rough until it ceases to be a valley. Its trend is approximately parallel to the Pacific coast and to the main structural trend of the Coast Ranges. The drainage basin of Santa Clara Valley is about 140 miles long and has a maximum width of/ about 45 miles; the area tributary to the valley south of latitude 37° 40' is about 3,100 square miles.1 The valley itself has a length of about 100 miles, of which 70 miles is south of San Francisco Bay, a maximum width of about 15 miles, and an area, exclusive of the part. occupied by the bay, of about 590 square miles, or about 380,000 acres. This report covers only that part of Santa Clara Valley lying south · of latitude 37° 40', but there is some land north of this line on the east side of San Francisco Bay that may properly be considered a part of the valley.
