200 Bulletin of Laboratories of Denison University. [Voi. xi. 
terval is in some places filled by a mud-brown sandstone which 
Cope regards as the equivalent of Cretaceous No. i of Hayden’s 
section at Colorado Springs. 
Below the gypsum is a band of lemon yellow and still be- 
low this beds of vermilion red sand. It seems probable that 
Cope overlooked the upper two-thirds of the red bed series and 
that the 850 feet is greatly over-estimated, yet it must be ad- 
mitted that- there is still room for a very unusual development 
of the Dakota sandstone in this interval. The great variability 
in the thickness and frequent absence of this horizon is one of 
the remarkable peculiarities of the New Mexico Cretaceous. 
In the Nacimiento region adjoining that described by Cope the 
sandy series at the bottom of the Cretaceous is never as thick 
as 100 feet, and consists of yellowish and white sandstone of a 
massive but very pulverent nature while south of Mt. Taylor 
there comes in a bed of yellow sandstone of about 200 feet 
thickness below this horizon. 
The gypsum is supposed to mark the top of the Jurassic, 
the thickness being given at 600 feet, while below it is the Tri- 
assic to which 1000 feet are ascribed, though the bottom was 
not seen. Cretaceous No. 2 with a thickness of 1500 feet follows 
the gypsum. It is composed of shales and contains the fossils of 
our “ Gasteropod Beds ” and probably also the “ Cephalopod 
Shales ” though it is not possible to determine what limits were 
selected in Cope’s classification. To this division a thickness of 
1500 feet is ascribed and it is followed by the sandy Creta- 
ceous No. 3, also 1500 feet thick. This probably embraces our 
Punta de la Mesa sandstone and part of the Prieta Mesa section 
above it. 
The thing that strikes one in reading Professor Cope’s pa- 
per is the enormous exaggeration of all estimated heights. It is 
probable that the total thickness on the Mesozoic strata which 
he gives at 5600 feet must be halved. It has been our exper- 
ience that an estimate made at a distance of the heights of ex- 
posures of these bright colored rocks is invariably too great. 
We have amused ourselves by making such estimates at a dis- 
tance of five and then of one mile and even then found it 
