The Maquoketa Shales. — James. 339 
Greenish shale, with alternations of calcareous and silicious layers, 
a few inches in thickness 7 ft. 8 in. 
Green silico-calcareous and argillaceous shales 11 ft. 6 in. 
A silico-calcareous or magnesian band 3 in. 
Greenish shale as above 12 ft. 
Concretionary layer, one to three inches 3 in. 
Shale with Lingulse 6 ft. 
A layer filled with a small Nucula or Tellinomya, and known 
as the Nucula bed, four to eight inches 8 in. 
A calcareous band cut by open joints or fissures, into which 
the materials of the layers above have penetrated 4 in. 
Dark olive shales, finely laminated and destitute of fossils. . . 3 ft. 4 in. 
Nucula bed, similar to that above, four to six inches 6 in. 
Total, 42 ft. 6 in. 
Reference is made in this report to the organic remains and 
the following species are illustrated but no descriptions are 
given : Nucula ( Tellinomya) fecunda, Clidophorus neglectus, 
Pleurotomaria micula, P. dejMuperata, Cyrtolites co7iradi, 
Bellerophon (Bucania) liratus, B. patersoni, T/ieca parvius' 
cuius, and Calyrnene mammillata''' 
In the same volume'" professor J. D. Whitney gives an 
account of the Hudson River shales of the state, in the course 
of which (pp. 179-180), he gives a section of the strata near 
Scales Mound station, which is in all essentials the same as 
that of professor Hall already quoted. He also notes the sec- 
tion on the Little Maquoketa river near Channingsville, Iowa." 
In 1866 professor J. D. Whitney'- mentioned an exposure of 
the Cincinnati group "near Channingsville, Iowa, on the Little 
Maquoketa river, first pointed out by C. Child s, Esq., of Du- 
buque." There is here a section, he says, of "about twenty- 
five feet of soft shales and layers, crowded with Orthoceratites, 
as well as Tellinomya {Nucula). Layers made up exclusive- 
ly of Orthoceratites., packed as closely as possible, are seen 
on the small streams a few miles west of Dubuque." 
This reference of the shales to the Cincinnati horizon ante- 
dates that of Dr. White by four years. Late Post Office guides 
contain no such office as Channingsville. The name has 
probably been changed, and may be now known as Lattners. 
In 1876 professor N. H. Winchell in his report" on Fillmore 
county, Minnesota, says under the head of Maquoketa shales : 
'The first eight are figured on page 55, and the last on page 432. 
"Ibid pp. 177-186. 
"See for this the next reference. 
'^Geol. Survey of Illinois, vol. I. p. 175. 
»Geol. and Nat. Hist. Survey Minn., 4th Ann. Rept. for 1875, p. 53, 
1876. 
