MESOZOIC EOEMATIONS. 
11 
of the depressions in this line, the erosion has displayed 
a considerable bed of lignite. It appears in four beds, 
which are represented in the following section: 
Feet. 
Sandstone No. 3- ' . 00 
Limonite... - 
Carbonaceous shale. 10 
Lignite. 10 
Sandstone. 00 
Lignite. 3 
Sandstone. 00 
Lignite. 3 ^ ^ 
Sandstone. 00 ^ 
Lignite. 3 o 
C 03 
Total.. 80 
D <r+- 
hi ® 
C ^ _ 
O'’ O 
This lignite bed extends throughout the region west 5'^ 
of the Rocky Mountains wherever No. ,3 occurs, and is 
the bed which has been mistaken for the true lignite, or 
p... 
No. 6 , by some geologists. It appears in this horizon ' ® 
H o 
wherever access is obtained, but is generally impure and p-S 
of little or no value. The beds differ in thickness at ag 
different localities ; their combined mass, with rather thin 
layers of slate, at one point reaching 50 feet. It is over- 3 a 
laid by a heavy bed of yellow sandstone, from which I |g 
obtained teeth of Sharks of the species Oxyrliinaf and “ £ 
Galeocerdo pristodontus, Agassiz. These yellow beds are 
v. (3> 
observable* for a mile to two miles west of the hog-back 
of Cretaceous No. 3, forming lines of low hills, from which s » 
. ^ ^ s 
I obtained numerous fossil MoUusca. These include Bacu- 11 
a a 
lites, Ammonites of two. species, including A. placenta, Ino- “S' 
ceramus, and a number of well-preserved Bimyaria and 
■ -• :g 
Gastropoda. I suppose these beds to represent Greta- “g 
ceous No. 3. 
P ’ 
A portion of their lowest member lies on the hard I-”- 
portion of No. 3, at some points, as already stated, form- 'Yi 
O w O' 
ing the upper part of the hog-back; at least, I obtained 
the Bacidites, an Ammonite, and the usual form of Inoceranms from sucli 
