A. F. Foerste — Clinton Oolitic Iron Ores, 29 



sections of the round iron ore grains are seen under the micro- 

 scope to be divided into separate areas, between which the re- 

 mains of the original bryozoans are still represented by calcite, 

 showing their original cell structure. A beautiful case of this 

 kind was collected by Dr. T. "W. Harris, of Harvard Univer- 

 sity, from the Clinton oolitic iron ore, two miles below Roch- 

 ester, New York, in the Genesee River, and kindly communi- 

 cated to me. 



The structures here described may, however, be observed 

 over a much wider area. Microscopically valuable specimens 

 were examined by me from the Clinton near Northumberland, 

 Pennsylvania, and at Wildwood Station, Georgia. In fact 

 these Clinton water- worn bryozoan remains are found through- 

 out the Alleghany fields wherever Clinton oolitic iron ores 

 occur. 



Similar sections were also obtained from the Clinton oolitic 

 iron ores at Todd's Fork, north of Wilmington, Ohio. 



As might be expected from the foregoing remarks, both the 

 bryozoan fragments and the cement filling their cells, since 

 both are composed of calcite, are frequently replaced so com- 

 pletely by the iron ore that no traces of their original structure 

 remains. All intermediate stages of alteration are of course 

 present. In no case, however, was any thing noticed leading 

 to the opinion that concretionary segregation of iron had 

 taken place, either around the bryozoan fragments or other- 

 wise. Simple replacement by iron ore was the rule, the attack 

 being made first on the exterior parts of the grains. 



The bryozoan fragments evidently belong to many species. 

 It would be rash to attempt to identify the species, since the 

 more fragile bryozoans of the Clinton Group have as yet 

 received little study. The branching forms, as might be 

 expected, are most largely represented. The most common are 

 forms having cells arranged in radiating manner around an 

 imaginary axis, but the bilateral Ptilodictydse and Stictsporidse 

 are also represented. I see no reason for believing them to be 

 other than good Clinton species. 



It might be interesting to speculate as to what reduced these 

 bryozoan remains to their present rounded forms. Of course 

 this must have been due to currents in the Clinton ocean. 

 But whether their presence is due to the waters of a shallow 

 sea or not, and whether they indicate the proximity of shore 

 conditions, I am not prepared to say. It will be pertinent, 

 however, to state that the shores of the Clinton sea do not 

 seem to have been far distant from the present metamorphic 

 axis of the Alleghany system, and that the oolitic deposits 

 mentioned from Ohio are found within 32 miles of the Clinton 

 conglomerate at Belfast, Highland County, Ohio. 



