344 The American Geologist. Junu, isoo 
10. Shale with Orthoceras, like No. 13 6 in. 
9. Limestone, with Orthoceras, like No. 15 1 ft. 
8. Shale with many graptolites and small shells 8 in. 
7. Comminuted shoUs, with Mnrchisonia 3 in. 
6. Shale with comminuted fossils like No. 8 9 in. 
5. Comminuted shells with a few perfect gasteropods 2 ft. 
4. Shale with Graptolites and LinguUe . . .\ 3 ft. 
3. Shale with numerous Hyolithes 3 in. 
2. Shale with graptolites etc., like No. 4, but largely barren. 6 ft. 4 in. 
1. Covered; probably like No. 2 3 ft. 
Total 31 ft. 3 in. 
The position of these shales and limestones is accurately 
given by Dr. White. They are the equivalent, and in fact the 
extension, of a part of the Cincinnati group as exposed in 
Ohio, definitely limited at the top and bottom. The junction 
of the series with the Galena limestone is shown on a small 
branch of the Maquoketa which empties into the main stream 
a mile or so below Graf. On the river itself at this point the 
typical, yellow Galena limestone is exposed, in places having 
a hight of from twenty-five to forty feet. The rock contains 
very few fossils and is in solid courses varying from four and 
six to twelve inches in thickness, the layers being separated by 
a few inches of shale. Following a road which leads up the 
small tributary, the Galena limestone is seen exposed to a 
limited extent. About half a mile above the mouth the shales 
begin to appear, and these a mile further up are to be seen in 
full force. The shales with graptolites, No. 2 of the section, 
as well as the layers with Orthoceras, are well shown. The 
junction of the two series. Galena and Maquoketa, can be ob- 
served in the bed of the little creek. The two are quite dis- 
tinct. The lower one. Galena, is a solid, yellowish limestone, 
showing a considerable amount of erosion on its upper sur- 
face. This is overlain by a tenacious yellow clay and this in 
turn by the blue shale as seen in the railroad cut. Thus an 
unconformity by erosion exists between the two formations. 
A short distance from the Post Office (Lattners), a small 
branch comes down from between the hills and empties into 
the river. Along this ravine there are a few exposures, at a 
higher horizon than the railroad cut. A yellow clay replaces 
the blue ; the Orthoceras layers are absent, but slabs containing 
Leptmyia sericea are found, as are also specimens of Strejptel- 
asma corniculum. Slabs of a dark, heavy limestone with 
polyzoa and brachiopods are occasionally found on the hill 
slopes. Quantities of chert containing a few fossils also oc- 
