Bulletin - United States Geological Survey, Issue 398

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The Survey., 1910 - Geology
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Page 74 - ... succeeding Lower Miocene series been as fossiliferous, however, as new localities have since shown it to be, or had it been followed into the localities where the great unconformity is more evident, it would have been less easy to confuse these earlier shales with their counterparts in the Miocene. As to the definite assignment of these shales to either the Eocene or the Oligocene in the time scale of California geology, that must be reserved for further study and for some future time.
Page 186 - ... the Tejon (Eocene) below or near the beds in question. If the Tejon is present under any particular sand or zone, then the abundance or scarcity of the oil depends largely upon (1) the proximity of the particular sand to the Tejon; (2) the state of disturbance of the underlying shale of the Tejon, or its relative position (whether unconformable or conformable) to the overlying beds; (3) the degree of porosity and grain of the sands of the zone; and (4) the effectiveness of the barriers hindering...
Page 140 - ... surface and obscures the structure. The formation occurs in the low hills bordering the valley and passes beneath the alluvium of the valley floor. The Etchegoin formation is nowhere within Coalinga district known to contain any petroleum, but like the Jacalitos it has an important relation to the accessibility of the oil. Some wells in the Coalinga field pass through a considerable portion or the whole of this formation before reaching the Jacalitos or lower formations. All wells drilled around...
Page 235 - It must be borne in mind, however, that absolute determination, by work on the surface, of the occurrence or nonoccurrence of oil in any one locality, is not possible. The best that can be done is to calculate the degree of probability on the basis of surface indications and structural conditions.
Page 181 - Diamond hole in the NE. $ sec. 26, T. 20 S., R. 14 E., was also put down about this time, and tended to discourage development in the southern part of the western field. In 1902 the California Oilfields (Limited) entered the Eastside field and soon began active operations in sees. 21 and 27, T. 19 S., R.
Page 15 - M. Wright, and many others who have contributed in one way or another to the value of the report. The writers also wish to express their gratitude to Mr. RB Marshall, geographer in charge, and to Mr. EP Davis, topographer, for hearty cooperation during the course of the field season, when the topographic and geologic work were progressing simultaneously. ADVANTAGE OF COOPERATION AMONG OPERATORS. The Coalinga oil field will continue to be the greatest in California if every operator will conserve...
Page 180 - ... and refined on a small scale. Although the oil was believed to have its source in underlying sands, nothing was known of their extent, or stratigraphic position. The first successful development, work was in 1890 when the Coast Range Oil Company, of Los Angeles, sunk a 163 foot well in Chico shale in the northern part of Sec. 20, T. 19 S., R. 15 E., from which gas and a little greenish oil of light specific gravity is said to have flowed. A windmill pump was attached to the well and ten barrels...
Page 113 - ... manner of mixture. This color has not been noticed in either of the other series and has generally been found to be a safe index to the identity of the Etchegoin beds. It has been noticed not only in the Coalinga field, but at McKittrick, near Buena Vista lake, at Mount Diablo, and on San Pablo bay. One or two fossil horizons are to be recognized in the Etchegoin beds, — one near their bottom and another some distance above; but whether these are persistent or not cannot be stated.
Page 90 - ... formation. The Santa Margarita formation is exposed in a strip along Reef Ridge and also in the East Side field. In the East Side field it consists of a basal member of about 300 feet of light-gray fine sand and clay that have a light bluish tinge when moistened. This member is overlain by the TamiosOma zone, which comprises a thickness of about 175 feet of fossiliferous, fine, medium-grained, and coarse, usually gray sand and minor amounts of conglomerate. This in turn is overlain by 400 to...
Page 22 - The ridge is a very definite natural feature, presenting an abrupt escarpment to the northeast, and forms the western boundary of the southern corner of Fresno County. It extends from about the head of Zapato Creek to a point south of the head of Avenal Creek. The name may well be used for the whole ridge. This name has not been passed upon by the United States Geographic Board. Avenal Ridge. — The name Avenal Ridge is here applied to the mountains separating Avenal Creek and McLure Valley from...

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