on 
on 
(0s) 
LOWER PART OF CEDAR VALLEY LIMESTONE). 
No. 3 ( 
No. 2 (= GyRocERAS BEDS OF CALVIN). 
r 
A 
A 
THE AMERICAN NATURALIST. [VOoL. XXXII. 
) A layer of calcareous shale or clay, 6 inches thick, containing 
mostly Brachiopods a 
(e) A bed of ie foloed imestone 2 feet in thickness, rich in fossils, 
especially Brachiopods, such as Sfirifer pennatus H.; S. i He 
Chonetes pusillum H.; Stro iis odonta demissa Conr.; S. perplana Conr.; 
Discina sp. A bran Eep Monticulipora eaa present di he 
middle of this bed. 
(d layer of greenish calcareous shale, 6 inches thick, with fossils 
like those in the ledge below. Strophodonta perplana Conr. more 
abundant. 
(c) A ledge of limestone, about 16 inches in thickness, of a dull dove 
color, fine and massive below, almost a shell breccia wate: Rich in 
Bnichiopods: such as Spirifer = H.; S. pennatus H.; Atrypa aspera 
S.; Orthis iowensis H.; O. vanuxemi HL; O. aaia H.; Stropho- 
donta Mt Conr. ; S. pare D S. nacrea H.; and Chonetes 
N 
A ae of greenish calcareous Som 6 inches in thickness, con- 
aie mostly Brachiopods like those above. 
(a) A bed of limestone, 2 feet thick, penne: below of a gray c 
pact rock not dissimilar from No. 2 (2); above, it becomes T jami 
nated and more fossiliferous. Brachiopods predominate above, 
low. A seam in which fossils are etched and partially ree 
separates this bed from the ledge beneath 
(d) A ledge of limestone, about 2 feet thick, gray, compact, and 
strong, the upper part peas marked with yellowish or brownish blotches. 
Pri a fossils are: sdsiiting opora sp.; Favosites pA s Winch.; 
F. placenta Rom.; mi a davidsoni E. and H. ; eS gigas 
Owens de sy ait ibid Bill. ; ; Crstiphyilum american and 
; C. sulcatum Bill. ; Atrypa aspera S. ; and Spirifer. Also peng es 
ATN Eastm aki Ptyctodus ide N. and W. 
thin = ae of capa only a few inches in thickness, not 
always separated from the above; frequently containing thin seams 
of clay. reag enai ar wie omatopora are quite abundan 
(4) gray compact limestone, about 3 feet thick, invariably 
containing Phitiptra and Crepidophyllum near the top. Be e 
having most of the fossils found in the ledge below, it contains: Chon 
phyllum sp.; two or three species of Cystiphyllum ; one of Alveolites of 
fine, dense structure ans spheroidal form; several species of Gastropo 
and Trilobites; Phragmoceras ; and Ptyctodus tritors. 
A ledge about 2 feet th hick, consisting of a strong, finely granular, 
‘ad’ compact gray limestone, with a slight tinge of dusky straw color, 
gree divided by two seams near the middle. rincipal fossils 
are: several species of Favosites, Acervularia, and other Cyathophylloids; 
ini Spirifer subundifera M. and W.; Atrypa reticularis L. 
| (often with well-preserved spiralia). 
From the above it will be seen that the pisciferous beds 
near Rock Island lie within the equivalent of the Cedar Valley 
