Fauna of the Morrow Group 
63 
Carboniferous’' in a reconnaissance of northeast Oklahoma, 
This report contains the first faunal lists from these forma- 
tions, but unfortunately the fossils from the various horizons 
of the Boston group were not discriminated, the author stat- 
ing that “most of the fossils came from the Archimedes [Mis- 
sissippian] and Pentremital [Pennsylvanian] horizons.”^^ 
In 1898,^ and again in 1900,® White repeated his statement 
concerning the Pottsville age of the coal-bearing shales of 
Washington County, Arkansas, and correlated the formation 
definitely with the Sewell formation of the Appalachian region. 
In a description of the general geology of the Ozark region, 
published in 1901, Adams^ described briefly the formations of 
the Morrow group, using Simonds’s nomenclature and again 
referring the Boston group to the upper part of the Missis- 
sippian. 
In 1904, the same author^^ in a discussion of the zinc and 
lead deposits of northern Arkansas described the Morrow as a 
variable formation embracing the Brentwood and Kessler lime- 
stone members and referred it to the Pennsylvanian series. 
Ulrich, discussing in the same paper the correlation of the 
formations described by Adams, referred the Morrow to the 
lower Pottsville on the basis of the widespread unconformity 
at its base and the Pennsylvanian aspect of the fauna. A pos- 
sible correlation with the Bend limestone and shale of central 
Texas was suggested and the question of the contemporaneity 
of the Morrow fauna with that described by Meek from “Old 
Baldy,” Virginia City, Montana, was raised. It was stated that 
the marine faunas of early Pottsville times existed, perhaps 
without interruption, in basins to the southwest of northern 
Arkansas and thence periodically invaded the latter region. 
The strata under discussion are mapped in the Fayetteville, 
Arkansas, quadrangle^^ as the Morrow formation, of early Penn- 
sylvanian age, containing the Brentwood and Kessler limestone 
members. Its description and correlation are essentially the 
same as in the paper referred to in the last paragraph. 
The Tahlequah, Oklahoma, quadrangle, adjoining the Fayette- 
ville toward the southwest, was mapped by Taff.^® The Mor- 
row formation is considered as a stratigraphic unit and is 
stated to consist of three classes of rocks: the sandy strata at 
