I believe that appearances point to the whole of the coal beds having been eroded, save the limited, steeply inclined portion at the foot of the mountains. A crowding of the strata against the mountains during the movements along the fault line, have given rise to the steep dip. The highest portion of the Tertiary beds has an elevation of 1,500 feet. A very even, gently sloping plain extends from this elevation toward South Riverside. It is formed of unconsolidated wash from the mountains, deposited on and dipping in the opposite direction from the Tertiary. The Tertiary formation consists of clays in various conditions of consolidation, others chalky in appearance, and a great thickness of argillaceous quartz-sand loosely cemented. Poorly preserved fossils are found in places. Near the southeastern corner of Mr. Hoag’s ranch is a hill with hardened concretionary sandstone outcropping around it. Nearly every portion of this contains fragments of bones supposed to be cetacean. Artesian wells are obtained near Temescal Post Office at a depth of 300 feet. The water is abundant and of excellent quality, and is flumed to South Riverside. Bunches of granite outcrop in the metamorphic rocks along the east side of Temescal Creek north of Dawson Cañon. At the dam of the San Jacinto Company there is a large outcrop of the beautiful diorite porphyrite, similar to that seen in Dawson Cañon. This extends northwesterly along Temescal Creek toward South Riverside, where it is quarried. It makes an excellent and durable building stone, being compact and free from much mica or hornblende. West of this is a narrow strip of coarse granite, followed by diabase. North of Mr. Hoag’s ranch, and west of the dam, is a dike of black porphyry. Westward the crystalline rocks are overlaid by the Tertiary. The dam commenced across the Temescal Creek at this point, where it enters the cañon, was intended to have been extended down to the bedrock, and thus bring to the surface the water which flowed beneath the surface channel. The diorite porphyrite is followed on the east by black porphyry. _Geology of the Temescal Tin District._—The Temescal Tin Mine is located in the northern part of the San Jacinto grant, and about 5 miles southeast of South Riverside. This portion of the grant consists of rolling hills. On the west is a large body of porphyry, extending nearly to the Temescal Creek.