162 
IOWA ACADEMY OF SCIENCE 
If the gray and blue limestones below the Bernalillo red shales of the Sandia 
district (Manzanan and lower Maderan) are to be thown together, which does 
not seem at all advisable, the term Magdalena Group as recently proposed* is 
clearly synonymic. Richardson’s title of Hueco groupt covers this section ex- 
actly, and has the great advantage of being at least recognizably defined. 
The Maderan series appears to be separable from the Manzanan upon the 
same faunal and other grounds as the Missourian and Oklahoman series in 
Kansas. Its development is that of a three-fold sequence. As exposed in the 
north, in the Sandia mountains the main limestone member is only 400 feet in 
thickness. Higher and higher limestone beds come in southward until a max- 
imum measurement of 3,000 feet is attained. This superior dark limestone 
formation, or median member of the series, is included in the Hueco forma- 
tion of Trans-Pecos Texas. If the name Hueco is to be retained as a geologic 
title it may advantageously be applied to the median members as representing 
the main body of limestone of western Texas. 
The third and youngest member of the Maderan series is composed of shales 
and sandstones having a characteristic red coloration. The title Bernalillo 
shales has been applied to them.t The fact that the “Red-Beds” are not of 
Permian nor Jura-Trias age is not a new discovery as lately announced by 
Lee.l As early as 1900 Herrick** had found abundant fossils in these beds 
which were correlated with the so-called Permian (Permo-Carbonic) of Kansas. 
It must be remembered that all of this author’s later references to the Permian 
are to this so-called Kansas Permian and not to the true Permian. About the 
first revision which my own preconceived notions of the region underwent 
when first I visited New Mexico in 1902, was that these Red-Beds of the Rio 
Grande region corresponded faunally to the Oklahoman series of Kansas. They 
were thus specifically correlatedtt and their distinctness from the Kansas Red- 
Beds emphasized by the designation of the local title of Bernalillo shales. At 
the time it was thought that the upper one-third of the red-beds section might 
be a part of the Cimarronian series; but it w^as soon afterwards discovered 
that over thi. part of the region of central New Mexico both the Kansas Red- 
Beds and the Triassic Red-Beds were absent.* In the section east from the 
Manzano mountains, down the Rio Pecos and Canadian river valleys there are 
thus found three great red-beds formations imposed upon one another with 
apparently no sharp planes of separation and belonging to three distinct geologic 
ages. To avoid confusion I have tried to be always very careful to apply the 
title Red-Beds only to this great sequence. There are in the region extensive 
Cretacic “red-beds,” which I have always referred to as the Pink beds, or Ter- 
tiary “red-beds,” and farther south great Devonian “red-beds,” which I have 
not designated at all. 
To further complicate the Red-Beds problem southward from the Sandia 
locality the sandy materials rapidly increase and the red coloration fades, as 
it does in the Red-Beds region of Kansas and Oklahoma. In the 150 miles 
^Journal of Geology, Vol. XV, p. 812, 1907. 
-fUniv. Texas Min. Sur., Bull. 9, p. 32, 1904. 
tOres and Minerals, Vol. XTI, p. 48, 1903 ; also. Kept, of Governor of New Mexico to 
Secretary of Interior, for 1903. p. 339, 1904. 
gJournal of Geology, Vol. XV, pp. 52-58, 1907. 
**Journal of Geology, Vol. VIII, p. 116, 1900. 
iiLoc. cit., p. 339, 1904. 
*Amer. Jour. Sci. (4), Vol. XX, pp. 423-429, 1905. 
