16 BIBLIOGRAPHY OF NORTH AMERICAN GEOLOGY, 1906-1907. 
Arnold, Ralph — Continued. 
63. Geology and oil resources of the Summerland district, Santa Barbara 
County, Cal.— U. S. Geol. Survey, Bull. no. 321, 93 pp., 17 pis., 3 figs., 1907. 
64. The Santa Maria oil district, California. — Abstract: Science, new ser,, 
vol. 25, p. 825, May 24, 1907. 
The Santa Clara Valley, Puente Hills, and Los Angeles oil districts, southern 
California. — See Eldridge and Arnold, no. 779. 
Arnold, Ralph, and Anderson, Robert. 
65. Diatoinaceous deposits of northern Santa Barbara County, Cal. — U. S. 
Geol. Survey, Bull. no. 315, pp. 438-447, 1907. 
66. Preliminary report on the Santa Maria oil district, Santa Barbara 
County, Cal.— U. S. Geol. Survey, Bull. no. 317, (39 pp., 2 pis., 1 fig., 1907. 
Describes the stratigraphy and structural conditions of the field and the economic 
developments. 
67. Geology and oil resources of the Santa Maria oil district, Santa Barbara 
County, Cal.— U. S. Geol. Survey, Bull. no. 322, 161 pp., 26 pis., 1907. 
68. Metamorphism by combustion of the hydrocarbons in the oil-bearing 
shale of California. — Jour. Geology, vol. 15, no. 8, pp. 750-758, 2 figs., 1907. 
Ashley, George Hall. 
69. Cannel coal in the United States.— Min. World, vol. 23, pp. 90-92, 381- 
383, 8 figs., 1905. 
70. An area of faulting in central Pennsylvania. — Abstract : Science, new 
ser., vol. 23, p. 33, January 5, 1906. 
71. Clearfield coal field, Pennsylvania. — U. S. Geol. Survey, Bull. no. 285, 
pp. 271-275, 1 fig., 1906. 
Describes the geologic structure of the field and the character and occurrence of the 
coal beds. 
72. Notes on clays and shales in central Pennsylvania. — U. S. Geol. Survey, 
Bull. no. 285, pp. 442-444, 1906. 
Gives a general description of the clays and shales of the region and particularly of 
the flint-clay deposits. 
73. The geological prelude to the San Francisco earthquake. — Pop. Sci. 
Monthly, vol. 69, no. 1, pp. 69-75, 6 figs., July, 1906. 
Gives an account of the geologic structure and geologic history of California. 
74. The maximum deposition of coal in the Appalachian coal field.— Econ. 
Geology, vol. 1, no. 8, pp. 788-793, 1906. 
Gives data regarding the thickness of coal seams in various Appalachian fields, with 
the view of determining the time required for the formation of the coal beds. 
75. The maximum rate of deposition of coals. — Econ. Geology, vol. 2, no. 1, 
pp. 34-47, 5 figs., 1907. 
From the study of peat bogs and field study of coal basins endeavors to determine the 
rate of accumulation of coal. 
76. Were the Appalachian and eastern interior coal fields ever connected? — 
Econ. Geology, vol. 2, no. 7, pp. 659-666, 1907. 
The Punxsutawney and Glen Campbell coal fields of Indiana and Jefferson 
counties, Pa. — See Peck and Ashley, no. 1888. 
Correlation of coals. — See White and Ashley, no. 2549. 
Ashley, George Hall, and Glenn, Leonidas Chalmers. 
77. Geology and mineral resources of part of the Cumberland Gap coal field, 
Kentucky.— U. S. Geol. Survey, Prof. Paper no. 49, 239 pp., 40 pis., 13 figs., 1906. 
Describes the physiography, stratigraphy, and geological structure of the region, and 
in detail the occurrence, character, geological relations, and correlations of the coal 
