THE MIDDLE COAL MEASURES 587 
portion of the old Middle Coal Measures. As now defined, this 
median member forms a single well-defined formation, with cer- 
tain uniform characteristics, and may be well recognized as a 
distinct unit. Toward the north limestones are thinner and 
more numerous, while to the south they come together and 
thicken, until in Kansas they form two well marked beds to 
which Haworth has given the names Oswego and Pawnee. The 
Henrietta limestone of Marbut* in southwestern Missouri seems 
to include these two limestones with an intervening shale bed. 
The whole forms a well defined escarpment which Marbut has 
traced across the southwestern portion of that state. No 
detailed section of the Henrietta formation has yet been 
published, so that the correlation of its individual beds cannot 
yet be made. In north central Missouri the formation seems to 
resemble more closely the beds found in southern Iowa, since 
the Mystic coal is widely recognized in Putnam, Schuyler, and 
Adair counties. The whole series of sections would seem to 
indicate a gradual change of character, from the near shore beds 
of the Raccoon River section to the off shore beds of Kansas. 
This change is very gradual as the series of sections is taken 
parallel to the strike. 
For this median member of the Des Moines series no good 
term has yet been proposed. The designations used in Kansas 
refer to individual parts of the formation. The name Henrietta 
and Appanose have been applied to distinctive phases of the 
formation. No general term has yet been used for the Raccoon 
River beds. If it is thought best to apply to the whole forma- 
tion one of the names already in use, it would seem that Appa- 
noose would have precedence as being first clearly defined and 
located. There are, however, objections to this since the Appa- 
noose formation as now defined is coextensive with an impor- 
tant coal bed and hence has a definite economic significance. 
Henrietta has been used in the general sense here suggested, 
* Missouri Geol. Sury., Vol. X, p. 44, 1896. 
2 Proc. Iowa Acad. Sci., Vol. I, Pt. IV, p. 36, 1894. 
3 Keyes, Proc. Iowa Acad. Sci., IV, 23; and Eng. Mining Jour., Feb. 26, 1898, 
