Art. IX.] Herrick-Johnson, Geology of the Alhuquerque Sheet. 199 
Group but included the Fox Hills division with the Laramie, 
presumably because of the presence of important lignite beds 
in both groups. 
Captain Dutton has given sections of the stratified rocks of 
the Zuni plateau which would be of great value if they rested 
upon any adequate paleontological foundation. He obviously 
is in error in his identification of the Triassic, to which he ascribes 
a thickness of 1600 feet. At the base of the Cretaceous as 
here exposed he places the Dakota sandstone with a thickness 
of 250 feet. The Colorado shale series is said to measure 1200 
feet and it is followed by 900 feet of lower Fox Hills and this ’ 
in turn by 550 feet Upper Fox Hills and this by 800 feet of 
Laramie. Each of these divisions is separated from its neigh- 
bors by a bed of massive sandstone from 125 to 175 feet thick 
which is not reckoned in nor ascribed to any group. The total 
thickness of the Cretaceous, including the Laramie is made to 
foot up to 4125 feet. 
Holmes had given in Hayden’s report for 1876 a section of 
the San Juan valley in which from 500 to 800 feet of variegated 
marls and soft sandstone beneath the hard sandstone of the 
Dakota had been added to that group but it is obvious that 
these marls belong to our Vermilion beds or Jurassic group. 
In Vol. IV, of the report of Surveys West of the lOO 
Meridian Professor Cope, in his introduction to the report on 
Mesozoic vertebrate fossils, offers a brief account of the strati- 
graphy of the region north of the Nacimiento range and, while 
it is difficult to follow his description and numerous inaccuracies 
appear in his estimates, it is yet interesting to see how this re- 
gion impressed the great paleontologist in 1876. 
The exploration was carried on from the valley of the Rio 
Grande to the region of the Gallinas and head waters of the 
Puerco via the Rio Chama. In the canon of the Cangilon he 
encountered our red beds with the gypsum horizon apparently 
in the same relative position as in the Nacimiento region. Be- 
neath it are the red and yellow sand and a thin layer of shale. The 
gypsum is in places 50 feet thick and is separated from the 
lowest Cretaceous by an interval of about 850 feet. This in- 
