GENERAL SUMMARY 267 



Eldridge, 1901. In his report on the Asphalt and Bituminous Rock 

 Deposits of the United States in 1901 * Mr Eldridge describes many in- 

 trusions of asphalt and bituminized sands in various parts of the United 

 States. Veins or dike like deposits are cited from the following states : 



California. — In the Point Arena district, 110 miles north of San Fran- 

 cisco, joints in shales, filled with bitumen, are mentioned (page 380). In 

 the Santa Cruz district, some of the dikes at the asphalt quarries, described 

 in the preceding pages of the present paper (notably numbers 23, 24, and 

 26) are mentioned and figured.f 



In the Santa Maria district asphalt veins which intersect Miocene 

 shales and overlying Pliocene sandstones are described and figured. J 

 They give off branches and are very irregular in thickness. Asphalt 

 veins are noted in the Las Alamos region, in Santa Barbara county. § 



A number of asphalt veins are noted and described in the southern 

 coast region (west of the Santa Ynez range) and in the asphalt district, 

 50 miles west of Bakersfield.|| 



Utah. — The uintaite, wurtzlite, nigrite, and azocerite veins of Utah are 

 described, and a number of them are figured.^ 



Colorado. — An asphalt vein in the Middle park, Colorado, is described.** 



Indian Territory. — Veins are mentioned in the Ten Mile district,tt the 

 Page district, JJand the Buckhorn district, §§ and in the Brunswick dis- 

 trict. III! Veinlets of quartz sand are also mentioned.^ff^ 



West Virginia. — The Ritchie County Grahamite vein is described, and 

 the origin of the vein is discussed.*** 



Branner and Newsom, 1901. A paper describing some of the dikes 

 west of Santa Cruz, California, was read before Section E of the American 

 Association for the Advancement of Science, at Denver, August, 1901. 



Branner, 1902. A dike of limestone in shale in the bed of Searsville 

 creek, 4 miles southwest of Stanford University, was observed by Doctor 

 Branner in 1892. 



Arnold, 1902. In an unpublished paper, in 1902, Dr Ralph Arnold 

 maps and describes a number of hard fine grained limestone dikes cut- 

 ting igneous tufas on the west slope of the Santa Cruz mountains, 7 

 miles southwest of Stanford University, California. 



General Summary 



• Following is a summary of some of the facts brought out by various 

 writers in regard to the character and origin of clastic dikes, including 



♦Twenty-second Ann. Report U. S. Geol. Survey, pt. i, pp. 209-464. 



tPp. 386, 388 et seq., 403, 405, 407, pis. Ixvii, Ixviii. 



JLoc. cit., pp. 426-4-29. **Loc. cit., pp. 327-330. |{|| Loc. cit., p. 310. 



§ Loc. cit., pp. 438, 439. ft Loc. cit., pp. 267, 268. 1f^ Loc. cit.,'p. 305. 



II Loc. cit., pp. 441-452. U Loc. cit., p. 270. *** Log. cit., pp. 233-238. 



^ Loc. cit., pp. 331-364. g§ Loc. cit., pp. '283, 295, 296. 



XXXVIIl— Bull. Geol. Soc. Am., Vol. 14, 1902 



