504 NEW YORK STATE MUSEUM 



that the Utica bed's change toward the Hudson valley in litho- 

 logic character and approach more closely the aspect of the Lor- 

 raine beds; and hence the former could not be recognized in this 

 region by their lithologic character, as former geologists have at- 

 tempted to do. 



It is farther stated by Ford that " the rocks at Schenectady 

 continue to the eastward to Eexford Flats where a break occurs, 

 and from that point all the way to the Hudson ^he rocks are 

 greatly tilted. The break here alluded to, Dr Emmons con- 

 sidered identical with the fault occurring at Saratoga Springs 

 and Bakers falls, and believed it to pass somewhere between Al- 

 bany and Schenectady, and to be traceable in its effects as far 

 south as Kingston." The demonstration of this break between 

 the tilted strata of the Hudson river region and the undisturbed 

 beds of the Mohawk valley is of great importance for our investi- 

 gation, as it refutes the argument presented by Mather, Hall and 

 Walcott, that the Hudson river beds of the Hudson river region 

 are continuous with and can be traced along the Mohawk valley 

 to the Utica and Lorraine beds of that valley. As the lamelli- 

 branchs, cited by Hall from Cohoes, and other fossils found by 

 the writer at the same locality (see farther on) prove, the Lor- 

 raine formation is well represented at the lower Mohawk, while 

 on the western side of the fault, the Utica shale, as claimed by 

 Ford, may be found. Hence there is no continuity along the lower 

 Mohawk. Similarity of lithologic characters can, in the great 

 mass of similar argillaceous shales, arenaceous shales, sand- 

 stones, grits and argillites, representing the Hudson river series 

 of beds in the Hudson valley, only, if ever, be relied on in dis- 

 tinguishing the formations after the most minute study of these 

 lithologic characters. The description of the localities in an- 

 other part of this paper will bear out this statement. 



N. H. Darton 



The same fruitful year brought out another discovery of fos- 

 sils in the Hudson river shales, that by Nelson H. Darton 

 (ii2/) near Sugar Loaf, 2 '{I. miles southwest of Newburgh and at 



