200 INDEX TO THE STRATIGEAPHY OF NOETH AMERICA. 



[Part of] synoptical taile of geological formations about Ottawa, Canada — Continued. 



System. 



Formation . 



Character of strata, etc. 



CharacteriBtic fossils. 



Thickness. 



Birdseye and 

 Black River. 



Ordovician. 



[Cambrian.] 



Unconformity. 

 Pre-Cambrian. 



Fine-grained and com- 

 pact light-gray im- 

 pure limestones, ma- 

 rine and fossiliferous, 

 some beds massive, 

 others shaly and nod- 

 ular. 



Chazy. 



Calcif ero us 

 [Beekman- 

 town]. 



Light-gray impure fine- 

 grained and concre- 

 tionary and fossilifer- 

 ous limestones, ce- 

 ment rock. 



Yellowish-gray calcare- 

 ous and arenaceous 

 shales, rusty-weather- 

 ing, with phosphatic 

 nodules. 



Arenaceous shales and 

 sandstones and mag- 

 nesian bands, fine 

 grained and light yel- 

 low weathering, 



Magnesian limestones, 

 fine and coarse 

 grained buff-weather- 

 mg, hard and cherty, 

 at times soft and sac- 

 charoidal or arenace- 

 ous and holding cavi- 

 ties lined with crys- 

 tals of quartz, passing 

 down into arenaceous 

 layers or sandstones. 



Potsdam . 



Light-yellow or white 

 and light-colored, at 

 times rusty-weather- 

 ing sandstones with 

 conglomerates at the 



Stromatocerium rogosum 

 Hall, Receptaculiles occi- 

 dentalis Salter, Streptelas- 

 ma profundum Hall, Tetra- 

 diumjibratum Safiord, Col- 

 umnaria halli Nicholson, 

 Maclwea logani Salter, 

 Gonioceras anceps Hall, 

 Heliocotoma planulata Sal- 

 ter, Orthis tricenaria Con- 

 rad, Strophomena incur- 

 vata Shepard, Cyrlodonta 

 subtruncata Billings, Cyr- 

 toceras sinuatum B . , Onco- 

 ceras constrictum Hall, Ac- 

 tinoceras bigsbyi Stokes, 

 Orthoceras rapax B., Illx- 

 nus ovatusB.,1. conradi B . 



Leperditia canadensis Jones, 

 IsocMlina Ottawa J., Cama- 

 Totoechia plena Hall, Dinor- 

 this platys Hall, Orthis 

 (Hebertella) borealis, Bill- 

 ings. 



Lingula belli Billings, Modi- 

 olopsisparviiiseulaB., Cte- 

 nodonta n. sp., Cyrtodonta 

 breviuscula B., Serpulites 

 sp., Scolithus, n. sp. 



Orthis irhperator Billings, 

 Asaphus canalis Conrad, 

 Lingula lyelli Billings. 



Cryptozoon caldferum Daw- 

 son, Ophileta complanata 

 V a n u X e m , Hormotoma 

 anna Bill.,. 0. disjuncta 

 B., Orthoceras lamarcki B., 

 Pleurotomaria gregaria B., 

 Ribeiria calcif era B . 



About 150 feet. 



Ophileta sp. cf. 0. compla- 

 nata Van. Orthoceras sp., 

 Scolithus canadensis Bill- 

 ings, Climactichnites v:il- 

 soni Logan, Protichnites 

 septem-notatus Owen, 



About 20 feet. 



30 feet. 



150 feet. 



250 to 300 feet. 



About 200 feet. 



[Part of] synoptical table of geological formations about Montreal, Canada. 



