64 
Kirtley F. Mather 
the base, mapped as the Hale sandstone lentil, which decrease 
regularly in thickness toward the west until too thin to be 
mapped ; the limestones of the middle part of the formation ; 
and the shales with a few local beds of limestone, which also 
decrease toward the west, in the upper portion. The formation 
is placed at the base of the Pennsylvanian series and the sug- 
gestion is made that the Wapanucka limestone is probably the 
equivalent, in part at least, of the Morrow formation. 
In 1905, Girtyi^ published a brief discussion of the Morrow 
fauna and its relations to other mid-Carboniferous faunas. The 
presence of Pentremites and Archimedes above the Chester hori- 
zons was commented on and the Morrow was cited as the typical 
Pottsville fauna by comparison with which the age of many of 
the limestones of the west and southwest might be determined. 
Suggested correlations were made between the Morrow and the 
Carboniferous limestones of the Eureka District, Nevada, the 
Bend and Milsap of Texas, the Wapanucka of Oklahoma, and 
certain “lowest Pennsylvanian” formations of Colorado and New 
Mexico. 
The Muscogee folio, also by Taff,!^ treats the Morrow in much 
the same way as does the Tahlequah folio as summarized in a 
preceding paragraph. In this quadrangle which adjoins the 
Tahlequah toward the west, the formation is composed largely 
of limestone with a variable amount of shale in the upper por- 
tion. It decreases irregularly in thickness toward the northeast 
and rests unconformably upon the Pitkin limestone. The uncon- 
formity at the top of the Morrow formation is stated to be 
greater than in the more eastern localities where the contact 
with the Winslow has been observed. 
The last published folio of quadrangles in which the Morrow 
strata outcrop is that descriptive of the Winslow quadrangle, 
situated south of the Fayetteville area. The two formations, 
the Bloyd and the Hale, as described in a preceding section of 
this report, are recognized as stratigraphic units composing the 
Morrow group. The faunas of the limestone horizons in the 
group are briefly discussed and the conclusion is stated that 
they are more closely related to well-known Pennsylvanian 
faunas than to any known fauna in the Mississippian series. 
