328 New York State Museum 



an invasion from the south. The bryozoans comprise 

 about half the fauna. 



The Middle Clinton beds form a lenticular mass 

 wedging in from the east between the base and the upper 

 Clinton. Its eastern edge is "finally overlapped by the 

 Upper Clinton so that in the eastern part of Herkimer 

 county the latter and the initial deposit of Oneida con- 

 glomerate constitute the whole of the Clinton group as 

 there developed" (Ulrich). At Clinton there are 125 

 feet or more of greenish shales and sandstone layers con- 

 stituting the Middle Clinton. The top is marked by the 

 base of the oolitic iron ore at Clinton. Its base is some- 

 what doubtful. It may extend down to and include the 

 Oneida conglomerate or the basal part may include a 

 thinned representation of the Lower Clinton beds. For 

 these beds of shale and sandstone the names Kirkland 

 beds (Ulrich T7) and Sauquoit beds (Chadwick '17, '18) 

 have been proposed. The recognition of the Middle 

 Clinton in New York is based mainly on the fossil evi- 

 dence. There is a wealth of characteristic ostracods. 

 The Middle Clinton contains other fossils besides the 

 ostracods, but they are seldom abundant or well-preserved 

 and not many kinds have been found. The ostracod 

 Mastigobolbina lata is the most characteristic of the 

 Middle Clinton forms. Other species are M. vanuxemi, 

 M. clarki and Zygobolbina conradi. 



The Upper Clinton includes the Williamson shale, 

 Irondequoit limestone and Rochester shale. In the Clinton 

 section the oolitic iron ore and the 18 feet of bluish 

 or greenish shale above are correlated with the William- 

 son; the nine feet of clayey suboolitic limestone (two 

 feet) and calcareous sandstones and arenaceous shales 

 above to the Irondequoit limestone. The Red flux ore bed 



