Corr€)<pondencL 
213 
Prof. A. Hyatt has not i)ul)lished yet anything on his exploration, 
of a part of the Tucunicari region, in 1889. In conversation with me 
he said: "The fauna he has collected is an upper Jurassic fauna." 
He did not ask me to keep it as a secret, and I did not ask him the 
authorization to use his opinion in any of my papers. However I re- 
frained carefully to quote his view, if I remember right, for I cannot 
jRnd anywhere in my publications a reference to Prof. Hyatt's ex- 
pressed o])inion. In private letters, I may have said, that Prof. Hyatt 
agreed with me on the Jurassic age of the Tucumcari rocks ; and I do 
not see any harm in the author of the review to have given the name of 
Prof. Hyatt, as having sustained my opinion. If Prof. Hyatt j)ublishes 
his observations and comes to a different conclusion, he can correct 
his first opinion, which although not recorded in print, was certainly 
expressed in words to me. 
Now Prof. Ilobt. T. Hill's part in the question is rather curious, for 
it is erratic in the extreme. First he published the 18th of November, 
1888, the following ])iiragraph : "Tiie reaffirmation of the age of the 
Tucumcari section ... to be u])permost Jurassic, as originally 
described by ]\Iarcou." Then in April, 1892, he gave another conclu- 
sion upon the geology of Tucumcari, as follows: "The writer has 
twice visited the mesa Tucumcari. . . The table or summit de- 
scribed by C'apt. Simpson is covered with the typical Llano Estacado 
formation. . . Below this is a vertical escari)ment of 50 feet or 
more of typical Dakota sandstone, resting upon loose sands and clays, 
forming a slope identical in asi)ect and fossil remains with the Deni- 
son beds of the Washita division. . . . Beneath this is a large de- 
posit of the typical Trinity sands country, of white pack-sands, thin 
clay seams, and flagstones, while the base is composed of tlie typical 
vermilion sandy clays of the lied beds." 
Although all is fi/pical according to Mr. Hill, it is nevertheless difli- 
cult to see clearly what he means, for he gives no practical section of 
a single locality, like my section at Pyramid mount ; no fossils of any 
sort are (juoted, no place even on the whole area is named for an 
observation, and the thickness, stratigraphy and even lithology are 
all confused. If placed in a tabular view, in order to try to under- 
stand ,Mr. Hill's conclusions, we have the following stratigraphic series : 
Me. Hill's Sehies of 1H9'.> 
30feetor mori' of typk-al Diikntn ^lunV 
stone. 
Looup Piiiifls iiiul clays identical uitli the 
Dt'iiisoii hi'ds of the VVjisliita Division. 
No thickness. 
Larsre di'posit of typical Trinity sandc, 
witli pac'k-sands, thin clay si>ains and 
flagstono. No thickness given 
Typical vermilion sandy clays of the Hed 
heds. Nfi tliickness >.'iven. 
Makcou's Series of 18")3. 
G.— White limestone, 2 feet. 
F. — Yellow calcareous sandstone. ,50 feet. 
K. — Blue clay with liiiiiilnia /iinunrari 
and Ostna »iiirs/i/i, 311 feet. 
D. (". and B. White and yellow sand- 
ston.-s, IK^ feet. 
X'ariegated marls of the Kenper or Up- 
per Trias, .tOI) feet. 
