GUELPH FAUNA IN THE STATE OF NEW YORK I 29 



finely and perfectly laminated dolomite, quite free from fossils, but in Cedar 

 county the brachiopod fauna of the upper part of the Le Claire reappears in 

 great force, up near the top of the formation. It was laid down on the 

 uneven floor of the Le Claire formation. 



Bertram stage. An irregularly bedded, nonfossiliferous dolomite with- 

 out fossils. 



In volume 1 1 of the same report, the Anamosa and Le Claire stages are 

 grouped together under the designation Gower limestone. 1 The Anamosa 

 " phase " is said to consist of soft granular limestones (dolomites ? ) with 

 very few fossils, while the Le Claire facies is hard bluish gray limestone 

 (dolomite?) with numerous fossils. "These are often gregarious, and 

 while no complete list of species has been made out, the fauna is known to 

 represent that of the Guelph of Canada. The Le Claire occurs in places in 

 mounds 50 feet high and over, in which little semblance of stratification is 

 to be seen. The rock is brecciated or conglomeritic." [p. 305] 



This paper accepts the theory which had already been suggested by 

 Hall that "at the close of the Niagara huge mounds and ridges were built 

 on the bottom of the shallow Silurian sea, in part by the accumulation in 

 situ of corals, crinoids and molluscous shells, and in part by the drift of cal- 

 careous sediments under strong currents. That these reefs were near the 

 surface is attested by their conglomeritic character." 



Illinois. The reports of the Illinois Geological Survey [1-8] give no 

 data in regard to the occurrence of the Guelph in Illinois, as Worthen 

 declined to admit the Guelph nature of the Le Claire limestone [see above]. 



We have cited above, a number of typical Guelph species from Illinois 

 localities but we learn from Prof. Stuart Weller who has been intimately 

 concerned with the study of the Niagaran fauna that it is not now possible, 

 with existing exposures, to say what part of the species recorded as from 

 the "Niagara" of Illinois have actually been derived from the upper or 

 Guelph horizon. 



There are at Grafton 120 feet of a buff colored dolomite in regular 



1 Norton, W. H. Geology of Cedar County. 



