80 
Some Geological Problems — Calvin. 
son’s Quarry, Atalissa and all other points where limestone*con¬ 
taining Spirifera parryana is exposed. 
The yellow sandstones above the mouth of Pine creek there¬ 
fore are of the same age as the limestones near Buffalo. They 
are not even Chemung unless the limestones are also Chemung;: 
much less are they Lower Carboniferous or Kinderhook. 
Owen gives a recogaizable figure of Spirifera parryana as it 
occurs with the shell preserved in the Hamilton limestones 
along Pine creek, and another figure of a cast of the same 
species as it occurs in the overlying sandstones.* Both forms 
are described as Spirifera euruteines, but it is interesting to 
note that the specific identity of the two forms is distinctly rec¬ 
ognized, and that furthermore the beds containing them are- 
referred to the same period. 
No Kinderhook or Sub-carboniferous of any kind has been 
observed by the writer in the reg : on about Pine creek in Mus¬ 
catine county. A very complete section of the rocks of the 
region may be studiei in the bed and banks of Robinson’s 
creek, a small stream emptying into the Mississippi a short dis¬ 
tance below Montpelier. Near the mouth of the creek is the 
ledge of limestone already mentioned as exposed at low water, 
and extending out into the river for more than a hundred 
yards. This limestone is the same as that found at Hanson’s 
quarry, Pine Creek mills and many other points, and is char¬ 
acterized by the presence among others of the following fossil 
species: Spirifera parr yam, S. aspera, Atrypa reticularis, 
and Athyris vittata. Following up the channel of Robinson’^ 
creek we find,—1, beds of arenaceous shale with some thin beds 
of limestone, containing branching polyzoa, Atrypa reticularis, 
Strophodonta demissa, very large forms, and Orthis iowensis;f 
—2, argillaceous shale only a few feet in thickness and contain¬ 
ing no fossils;—8, layers of sandstone among which is a bed 
about 14 inches in thickness containing casts of Spirifera par¬ 
ryana, (S. capax) with which are associated either in the same 
bed or in adjacent beds both above and below, casts of Atrypa 
reticularis, Strophodonta demissa, Orthis iowensis, and Spiri - 
*Owen’s Geological Survey of Wisconsin, Iowa and Minnesota, Table 
III, figs. 2 and 6. 
1 No opportunity has yet been found to measure the thickness of the 
several members of the section. 
