372 The American Geologist. i^ec.Mni.ei-, 1893 
by nil' as far back as 1.S5I). as Triassic; and iiiorc as rcpri'senting: 
the Keuper and A'ariugated marls of Europe. 'I'lic ditt'erencc 
between Mr. Cuminins' thickness of those strata, and what 
] saw from Antelope hills to Rocky Dell creek and Pyramid 
mount (Tucumcari area), is difficult to be explained. My estima- 
tion is about 1,500 feet, when Mr. Cummins gives onlj' from 125 
feet to 400 feet, with an average of al)out 2(MI feet only. Tt is- 
possible that Mr. Cummins has referred one thousand feet of the 
strata, between Antelope hills and Kocky Dell creek, as Dyas 
(Permian); and has kept for his Trias the strata from the lowest 
part of Rocky Dell creek to the white and yellow sandstone of th(v 
Pyramid Mount section, which according to my estimate of thick- 
ness is about 500 feet. 
Now comes the Tucumcari stratigraphy, so admirably developed 
round the (Jreat and Little Tucumcari mountains. Monte Revuelto 
and Pyramid mount. In regard to Monte Revuelto. Mr. Cum- 
mins says: •• This mountain was by mistake called Big Tucum- 
cari on the maps published by Mr. Marcou. The Monte Revuelto 
and not Rivuelto as it is wrongly spelled l)y Mr. Cummins, term- 
inates the great mesa of the Llano Estaeado, just due south of 
Fossil creek. Tt is the most prominent peali and the best land- 
mark of the area, and it is not easy to make a mistake with. It 
was pointed out tons by some jMexicans traveling with our party,. 
and by some Indians of the Pueblo of San Felipe whom we met 
there. The Big Tucumcari, called now only Tucumcari mount,, 
is isolated t»y denudation and erosion in the great valley, called 
Plaza Larga by the Mexicans, north of the fjlano Estaeado. On 
Mr. Cummins" map, he took the Big Tucumcari mount for Monte 
Revuelto; and what he calls Big Tucumcari is truly the Little 
Tucumcari. As to his Little Tucumcari, it is a very small isolated 
hill, marked on my map, south of the true Little Tucumcari, but 
without any name. ^I}" geological maj) and the topographical 
map of lieutenant A. W. Whipple, of the Pacific Railroad ex- 
plorations, by the :55th parallel, l)0th surveyed and constructed 
in 1 85:>, are the only exact maps ever pulilished on the Tucumcari 
area, except a small sketch map, marked No. 4, in lieutenant J. H. 
Simpsons report of 1849, Washington, which gives also the exact 
position, of the Little and Big Tucumcari. The map of Mr. Cum- 
mins, in the Tliinl Ann. Rep. Gcol. Snrc. Texas, is at variance 
with the three first maps published, and according to right of 7*)/- 
