RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 255 



Feet. 



6. Dark brown to black carbonaceous shale with Triarthrus 

 spinosus, T. becki, T. glaber, Lcptograptus annectans, 

 Glossograptus quadrimucronatus, and other graptolites. 

 Gloucester formation. (New Name). 50-75 



5. Interstratified limestone and dark shale. Characteristic 

 fossils are Ogygitcs canadensis, Oxoplecia calhouni, Zygo- 

 spira uphami, Plcctambonites rugosus, etc. Collingwood 

 formation. 25-30 



4. Thick-beddetl dark gray limestone with very little shale. 

 Characteristic fossils are Fusispira subfnsifonnis, F. 

 nobilis, and many other gastropods, Cydospira bisid- 

 cata, Strophomcna trilobata, and, in the lower part, Ra- 

 finesquina deltoidea. Picton formation. 100 



3. Gray limestone, thin-bedded and with much interstrati- 

 fied shale in the lower twenty-five feet, less shaly but not 

 very thick-bedded above. "Prasopora beds" or true 

 Trenton. In the shale at the base Clitambonites ameri- 

 canus is the guide fossil, though many others are present. 

 In the strata a short distance above these a profusion of 

 echinoderms are found, among them being Pleurocystites 

 squamosus, P. filitcxtns, Agelacrinites inconditus, and 

 Comarocystifes punctatus. Prasopora simulatrix is so 

 very abundant throughout these strata that I have 

 usually spoken of them as the Prasopora beds. 100 



2. Coarse-grained light gray thick-bedded limestone, 

 thirty-three feet in thickness, resting upon sixty-six 

 feet of blue to gray fine- to coarse-grained limestone con- 

 taining great quantities of black chert in layers and 

 flattened cakes. The upper beds contain an abundance 

 of Stromatocerium and Solenopora and in a nearby 

 locality, Tetradium racemosum. The lower beds have 

 shaly partings in which great numbers of fine echinoderms 

 have been found, particularly crinoids. Among the 

 characteristic fossils are Edrioaster bigsbyi and Cleiocrinus 

 regiiis. Hull formation. 100 



1 . Thick-bedded dark gray limestone with partings of shaly 

 limestone containing numerous fossils, among them 

 Triplecia cxtans, Phragmoliics compressus, Ortkis dis- 

 paralis, Strophoniena filitexta, and Rcceptaculites occi- 

 dentalis. This formation is not well exposed at Ottawa. 

 Rockland formation. 35 



