6 THE BOOK CLIFFS COAL FIELD. 
been the only available systematic geologic reports of the region. 
The presence of coal in the Book Cliffs has long been known. The 
deposits are mentioned by R. C. Hills a in his report on the coal 
fields of Colorado, and by L. S. Storrs 6 in his paper on the Rocky 
Mountain coal fields. Arthur Lakes has also referred to part of 
the area c and has described the Book Cliff mine. d But the coal field 
was not examined in detail until 1905, when J. A. Taff, e of the United 
States Geological Survey, studied the western part of the field from 
the vicinity of Sunnyside to Castlegate, Utah, and its southern con- 
tinuation along the escarpment of the Wasatch Plateau. 
During three months of the season of 1906 the writer, assisted 
by W. D. Neal, L. J. Pepperberg, and C. D. Perrin, made a recon- 
naissance survey of the eastern part of the Book Cliffs field from 
Grand River westward to the termination of Taff's work. The 
attention of the party was devoted mainly to a study of the occur- 
rence of the coal. The boundary between the Mancos shale and 
the Mesaverde formation — the most easily recognized horizon near- 
est the coal — was followed throughout the field, but in the time 
available detailed mapping of the formations could not be attempted. 
The location of the Dakota sandstone outcrop below the Mancos shale 
and the position of the base of the Eocene above the Mesaverde forma- 
tion were determined only at certain localities, and the boundary 
between these formations, shown on Plate I by a dotted line, is only 
approximately located. 
TOPOGRAPHY. 
The Book Cliffs form the southern margin of the Book or Tavaputs 
Plateau, which is situated in the central part of the Colorado Plateau 
province, between the Rocky Mountains and the Wasatch Range. 
The southward-facing cliffs, which extend in a great east-west line 
from Grand River to Castlegate, lie north of and generally in sight 
of the Denver and Rio Grande Railroad and are one of the most 
striking topographic features along that railroad. The cliffs do not 
form an unbroken wall, but locally are deeply cut by small streams 
into a series of spurs which, although much lower than the main 
mass of the plateau to the north, tower above and dominate the 
great plain at their base. Tins plain is eroded in the soft shale 
underlying the coal-bearing rocks, and it affords a route for the 
railroad which closely skirts the foot of the cliffs throughout most 
a Hills, R. C., Coal fields of Colorado: Mineral Resources U. S. for 1892, U. S. Geol. Survey, 1893, p. 353. 
b Storrs, L. S., The Rocky Mountain coal field: Twenty-second Ann. Rept. U. S. Geol. Survey, pt. 3, 1901, 
p. 436. 
c Lakes, Arthur, The Grand River coal field: Mining Reporter, vol. 51, 1905, pp. 379-381. 
d Lakes, Arthur, The Book Cliffs coal mine: Mines and Minerals, vol. 24, 1904, pp. 289-291. 
«Taff, J. A., The Book Cliffs coal field: Bull. U. S. Geol. Survey No. 285, 1906, pp. 289-302. 
