IOO NEW YORK STATE MUSEUM 



Vanuxem, 1842. x In reporting on the Calciferous group in 

 the third district,- Vanuxem distinguished three varieties of the 

 rock : 



The first silicious, compact, and perhaps a continuation of the 

 Potsdam sandstone ; the second a mixture of yellow sand and car- 

 bonate of lime, in irregular layers, the mass from whence the name 

 Calciferous sand rock was derived; and third a mixture of the 

 Calciferous material, which is usually yellowish, and of compact 

 limestone, containing also some slaty matter. The action of the 

 weather gives these layers the appearance of a gothic fretwork. 

 These materials are often coated over with a greenish shale ; and the 

 whole mass has been designated, in the annual report, by the name of 

 Fucoidal layers. In the annual reports the fucoidal layers were 

 separated from the Calciferous sand rock, in consequence of always 

 observing that they were above the great mass of the latter rock; 

 overlooking the fact, as it seemed to be of little importance, that 

 the • fucoidal layers were always covered by a few, or more, layers 

 of the Calciferous rock. A reattention to the subject was caused 

 by the observations of Dr Emmons in the second district, where the 

 mass above the fucoidal layers is greater than the one below it ; the 

 combined observations of the two districts showing that the two 

 constitute a group, in which the fucoidal layers are included, and 

 therefore a subordinate mass. 



Fossils are rare in the Calciferous sand rock, but in the fucoidal 

 layers there are many individuals, though the kinds are few. Most 

 of them are peculiar to this rock. . . 



As a marked difference exists between the Calciferous sand rock 

 and the fucoidal layers, though they form one group from the in- 

 tercalation of the latter, they will be treated separately, from the 

 rule which separates objects which are different. 



Comment. The above excerpts, given substantially in Van- 

 uxem's own words, show plainly that this excellent observer was. 

 so impressed with the differences between the two formations 

 that he described them separately, and likely would not have 

 classed them together at all, except for the reported con- 

 ditions in the second district, unfamiliar territory to him. He 

 noted the differences in lithology and in the fossils, and also that 

 the fucoidal layers thin out westward, being very thin at Little 

 Falls. 



Emmons, 1842.- Emmons, in the second district, which in- 

 cluded the entire east and north sides of the Adirondack region, 

 found the Calciferous in greatest variety and in greatest thick- 

 ness. In the Champlain valley he included the lower Chazy in 

 the Calciferous, and in the lower Black River region, the beds of 



"Geol. N. Y. 3d Dist. p. 30-38. 

 2 Geol. N. Y. 2d Dist. p. 105-6. 



