10 THE BOOK CLIFFS COAL FIELD. 
between a quarter and a half mile wide, and traces of several other less 
distinct terraces have been found above this one. 
BOOK CLIFFS. 
The Book Cliffs occupy a belt from 1 to 10 miles wide and rise above 
the adjacent lowland from 2,000 to 6,000 feet. In places the rise is 
abrupt in one or two sharp precipices ; elsewhere it is accomplished by 
a series of cliffs and intervening benches. The rocks composing the 
escarpment are alternating beds of sandstone and shale dipping 
slightly northward, and the strata present the appearance of the leaves 
of a book lying flat, hence the name. 
In the area here discussed the cliffs extend in an S-shaped belt from 
Palisades to Sunnyside. At the east they are much dissected by 
Roan Creek, and a subordinate escarpment known as the Little Book 
Cliffs extends northwestward from the mouth of Hogback Canyon. 
The top of the Little Book Cliffs marks the crest of a ridge whose 
northeastern flank constitutes a dip slope, and the area between Little 
Book Cliffs and Roan Creek is a gentle northeastward-sloping mono- 
cline dissected by southeastward-flowing streams. 
West of the headwaters of Roan Creek the Book Cliffs proper extend 
to the end of the area mapped. Erosion by East and West Salt 
creeks has caused the rim of the plateau to recede so much that a few 
miles east of the Utah-Colorado boundary the distance between the 
lowlands and the plateau is unusually great. Between the State line 
and Green River the average distance is about 10 miles. Here a low 
bench, caused by a great lens of sandstone in the shale, forms the base 
of the cliffs, as shown in Plate II, A. Above this lowest bench there 
is a succession of dissected platforms and escarpments up to the 
summit of the plateau. 
Green River has cut another embayment in the cliffs, and Price 
River in its canyon course separates a small area, known as the Beck- 
with Plateau, from the main mass of the upland. The Beckwith 
Plateau is considerably dissected on the north and east, but faces the 
lowland on the west in a practically unbroken scarp more than 1 500 
feet high. Beyond Price River a similar line of cliffs extends at least 
as far as Sunnyside. The surface at the summit of this cliff slopes 
eastward and forms a platform upon which another but more 
dissected line of cliffs rises 1,500 feet higher. 
BOOK OR TAVAPUTS PLATEAU. 
The crest of the Book cliffs forms the southern rim of the Book 
Plateau, or, as it is known in Utah, the Tavaputs Plateau, which 
viewed from the south, forms an even-topped sky line. The plateau 
slopes gently northward toward the axis of the Uinta Basin, but is 
much dissected by deep canyons. 
