HAWORTH AND BENNETT.| General Stratigraphy. | 121 
river to the north it becomes narrower until the Nebraska line 
is reached. 
Characteristics.—The Winfield formation is “‘composed of a 
cherty limestone at the base with a massive concretionary one 
at the top, the two separated by yellowish shales. This chert 
and concretionary limestone form the highest prominent chert 
ledge in the Kansas Permian, and make a marked stratigraphic 
horizon that is of great assistance in determining the areal 
geology of eastern central Kansas.”’ 
Marion Limestone.102 
This name was given by Prosser and is applied by him to 
the rocks immediately above the Winfield formation and below 
the Wellington shales. 
Thickness.—Adams?!® says that its thickness has been esti- 
mated at between 300 and 400 feet. Later estimates show it to 
be but about 150 feet. 
Characteristics.—‘“Buff, thin-bedded limestones and shales 
form the principal part of this formation. The lower part is 
composed of rather soft, porous, thin-bedded and shaly layers 
to shales, containing near the base a considerable number of 
siliceous geodes and occasionally some chert. Some 50 or 60 
feet above the base is a buff limestone containing large num- 
bers of small lamellibranches, as Plewrophorus subcuneatus 
M. & H., Bakewellia parva M. & H., Yoldia subscitula M. &. H.., 
and other species, while about 20 feet higher is another similar 
limestone containing large lamellibranches, as Aviculopecten 
occidentalis (Shum.), Myalina permiana (Swallow) and Pseu- 
domonotis hawn M. & H. A limestone containing Plewro- 
phorus occurs in some localities near the horizon which also 
contains large cherty concretions.” 
102. Prosser, Chas. S.: Jour. of Geol., vol. 111, p. 786. 1895. 
108. Adams, Dr. George I.: U.S. G.S., Bull. 211, p. 60. 1903. 
