STBATIGRAPHY. 
17 
thick and is normally overlain by buff sandstone. But south from 
the prospect near the mouth of the canyon, on the west side, the 
coal locally disappears and its place is occupied by a thin deposit 
of whitish, ashlike material about a foot thick, and the overlying 
thin-bedded red sandstone is crumpled and broken, as if it had 
fallen consequent to the burning of the coal. Bits of slaglike material, 
clinkers, etc., are in the vicinity. 
The thickness of the coal-bearing formation is variable and decreases 
toward the west. Immediately east of Grand River the entire for- 
mation is exposed in steep cliffs, and a thickness of 2,200 feet was 
measured barometrically on the flanks of Grand Mesa. North of 
Thompsons, Utah, a thickness of about 1,800 feet was measured, 
but an allowance for dip makes this measurement less reliable. 
At the mouth of Horse Canyon, in the west end of the field, the 
formation is only about 1,200 feet thick. As stated on page 19, the 
erosion of the Mesaverde before the deposition of the overlying 
Tertiary rocks is probably the cause of the observed difference in 
thickness. 
Fossils occur in this formation at several horizons and include 
invertebrates, leaves, and a few bones. Shells were found in many 
localities between 200 feet above the lowest coal bed and 250 feet 
below the overlying varicolored deposits. Among the fossil shells 
Stanton has identified the following species: 
Fossils from Mesaverde formation . 
Ostrea sp. 
Ostrea glabra M. and H. 
Anomia gryphorhynchus Meek. 
Anomia micronema Meek. 
Modiola laticostata White? 
Modiola cf. regularis White. 
Unio, several species. 
Corbula perundata M. and H. 
Corbula subtrigonalis M. and H. 
Corbicula cytheriformis M. and H. 
Campeloma? sp. 
Tulotoma thompsoni White. 
Goniobasis sp. 
Molluscan burrows in fossil wood. 
A number of small lots of fossil leaves were collected from this for- 
mation at several localities, and at a few places fairly good collec- 
tions were obtained, which were identified by F. H. Knowlton as 
follows : 
About a quarter of a mile northwest of the present Book ( liil' mine, 
from a sandstone 30 feet above the upper coal, the following were col- 
lected: 
Fossil leaves from sandstone near the Book Cliff mine. 
Sequoia Reichenbachi (Gem.") Heer. 
Eriocaulon? porosum Lesq. 
Palm (new). 
Near the mine entry several specimens of HalymeniU s ma jot 
were obtained. 
Ficus latifolia (Lesq.) Knowlton 
Myrica Torreyi Lesq. 
Magnolia sp. 
'esq. 
(i:W54— 09- 
