Show Study Areas

San Benardino:
The San Bernardino area is a semiarid inland valley of about 120 square miles in southwestern San Bernardino County, about 60 miles east of Los Angeles, in the upper part of the Santa Ana River drainage basin. The San Bernardino area was defined by Dutcher and Garrett (1963) as a northwest-trending area between the San Andreas and San Jacinto faults. The area is bordered on the northwest by the San Gabriel Mountains, on the northeast by the San Bernardino Mountains, on the south by the badlands and Crafton Hills, and on the southwest by a low, east-facing escarpment of the San Jacinto fault. Alluvial fans extend from the base of the mountains and hills that surround the valley and coalesce to form a broad, sloping alluvial plain in the central part of the valley. Altitude ranges from about 1,000 feet (ft) near the city of San Bernardino to more than 10,000 ft in the San Bernardino Mountains.

Yucaipa:
The study area extends from the San Andreas Fault in the north to the San Timoteo wash in the south, and from the Crafton Hills in the west to the hills east of Yucaipa. Between the hills and mountains is a gently sloping area of unconsolidated deposits, commonly referred to as the Yucaipa plain. On the northwest side, the plain merges into the San Bernardino valley, and on the southeast side, the plain opens to the San Gorgonio Pass. The Yucaipa plain ranges in altitude from about 1,800 to 3,600 ft above sea level and surrounded by hills and mountains that range in altitude from about 3,000 ft in the Crafton Hills, to 5,000 ft along the ridge of the hills east of Yucaipa, to more than 8,000 ft in the San Bernardino Mountains.