STRATIGRAPHIC POSITION OF WESTERN RED-BEDS. 
BY CHARLES E. KEYES. 
In Iowa some very important parts of the general Carbonic section are 
missing. Of these unrepresented portions none is so widely interesting at the 
present time as the part commonly called the Red-Beds. The very name is 
itself indicative of the uncertainties surrounding the proper geologic affinities of 
the formation. Until very recently the Red-Beds formation has been one of the 
enigmas of American geology. The Red-Beds have steadily resisted all at- 
tempts to unravel the secret of their geologic age. The key to the puzzle ap- 
pears finally to he found in the far-off Mexican tableland. 
If the doubtful Fort Dodge gypsum beds are excepted, and special attention 
will be directed to them later, the nearest localities to Iowa where undoubted 
Red-Beds are definitely known to occur are in central Nebraska and Kansas. 
In the last mentioned state no mention has ever been made of any evidence 
suggesting that the Red-Beds follow the other Carbonic strata in any other 
than strictly unbroken sequence. In the southern Rocky Mountain region and 
in the northern part of the Mexican tableland, in eastern New Mexico, the 
beds in question have been found of late to have unconformable relationships 
with the other Carbonic beds beneath.^ 
The geologic age of the Kansas Red-Beds has long been a matter of con- 
troversy. By some authors they were considered as all of Permian age; by 
others all of Triassic age. But in New Mexico, quite recently, it has been dis- 
covered that the lower part of the Red-Beds section is really Late Carbonic 
(Oklahoman series) in age; while the upper part is of Triassic age; and that the 
two divisions are separated by a well-marked unconformity.^ It has been also 
found in the New Mexican region that there are other extensive Red-Beds 
which belong neither to the Carbonic nor the Triassic ages, but to the Devonian, 
Cretacic, and even Tertiary ages.® 
The so-called Permian* Red-Beds of Kansas are now called the Cimarronian 
series.® In Nebraska, Kansas, Oklahoma and Texas this great series immedi- 
ately follows, without as yet recognized unconformity, as has been stated, the 
Oklahoman series, which succeeds the Missourian series, so well represented in 
southwestern Iowa and northwestern Missouri by our Upper Coal Measures. 
Far to the southwest, in southern New Mexico, in a lofty range known as the 
Guadalupe mountains, there lies above a great section of blue limestone which 
1. Am. Jour. Sci. (4) , Vol. XXI, p. 296, 1906. 
2. Am. Jour. Sci. (4), Vol. XX, p. 426, 1905. 
3. Journal of Geology, Vol. XVI, p. 445, 1908. 
4. Journal of Geology, Vol. VII, p. 321, 1899. 
5. Colorado College Studies, Vol. VI, p. 3, 1896. 
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