walcott.] CORRELATION. 397 



secondary rocks met with and is very abundant in all that part of the 

 plain immediately adjacent to the Rocky Mountains which he had ex- 

 amined. A similar rock is met with in the eastern part of the State of 

 New York. Specimens from many parts of the strata on the Canadian 

 River are entirely similar to those quarried in New Jersey and used 

 in great quantities in the cities of New York, Albany, etc., for build- 

 ing. 



u Whether this sandstone is in all respects similar to the 4 Old Red 

 sandstone ' of Werner, which makes so conspicuous a figure in the 

 systems of certain geologists, we are not able to say. It, however, 

 certainly occupies a place similar to the one which has been assigned 

 to that rock." In a foot note referring to this statement it is said 

 that — 



This red sandstone is first found on the waters of the lakes on the strait between 

 Lake Huron and Lake Superior, and forms the fall called the Sault de Ste. Maria. 2 



It also occurs in the Catskill Mountains and in the Salt District in the western part 

 of the State of New York, having a similar relation to the secondary rocks in that 

 quarter. * * * The red sandrock now under consideration appears at one place 

 with every character requisite to place it among the rocks of transition, at another* 

 it is manifestly secondary ; yet its continuity may be traced through minute shades 

 of gradation or by a sudden transition from one of these points to the other. 2 



A review of the preceding remarks indicates that Dr. James sup- 

 posed the Jura-Trias sandstone of the eastern foothills of the Rocky 

 Mountains, the red sandstone of the Lake Superior region (Algonkian), 

 the eastern New York sandstone (Upper Cambrian), and the New Jersey 

 Triassic sandstone were of the same relative geologic age as shown by 

 their lithologic characters and supposed stratigraphic position. 



Balceivell. — The publication of the American edition of Mr. Robert 

 Bakewell's Geology in 1829 was an important contribution to American 

 geologic literature. It presents an account of the geological distribu- 

 tion of organic remains as then understood and the general principles 

 of geology as known to English geologists. 



In regard to correlation by fossils Mr. Bakewell says : 



•With respect to fossil conchology he is inclined to believe that the attempt to iden- 

 tify the strata of distant countries by the isolated occurrence of any particular species 

 of shell has been carried further than a sound induction from facts or analogy would 

 warrant. His opinion on this subject, given in the second edition of this work, he 

 will here insert: "It may be doubted whether the occurrence of similar organic 

 remains is sufficient to identify strata in distant parts of the globe; for could we 

 admit that strata are universal formations and extended from the frozen to the tor- 

 rid zone, it seems more than probable that the animals that lived on any one partic- 

 ular stratum would be of very different species in different latitudes." * * * 



In strata belonging to one formation and in adjacent districts, the existence of cer- 

 tain shells, whether we regard them as distinct species or as varieties, may be of use 

 in identifying any particular bed ; and in distant countries where we find the same 

 remarkable species of shell associated with any other remarkable species in consid- 

 erable numbers it may serve to identify a particular rock formation, where the min- 

 eral character of the rock may be very different from that in which the observer has 



1 Op. cit. , p. 205. 2 Op. cit , p. 206. 



