296 PIONEERS OF SCIENCE IN AMERICA. 



Ichnological Cabinet at Amherst College, and completely fill a 

 room one hundred by forty feet, besides two smaller apart- 

 ments. The number of distinct impressions studied and 

 labelled exceeds twenty thousand. It is likely that some of 

 the suggestions of the Ichnology may not be verified. It would 

 be strange if the following thirty years of discovery should 

 not enable paleontologists to declare positively whether the 

 Batrachoides impressions are really the mud nests of tadpoles, 

 or whether the " insects " are properly larval or adult hexapods, 

 or simply Crustacea, as urged by Dana and Agassiz. 



In 1857 Prof. Hitchcock accepted the appointment of State 

 Geologist of Vermont. Though the appropriation was very 

 small the work was energetically prosecuted, and conclusions 

 presented in five years' time in two quarto volumes of nearly 

 one thousand pages. Not many speculations were indulged 

 in, though opportunity was afforded for propounding new and 

 startling theories of the metamorphosis of rocks. The report 

 was issued just at the time when Barrande had discharged his 

 artillery at the opponents of the Taconic system, and compelled 

 American paleontologists to assign the Olenellus to the primor- 

 dial zone instead of the Hudson River slates. The report 

 had been written to accord with the American- view, but the 

 authors were enabled to omit everything that did not illustrate 

 the reference of the slates to the Cambrian terrane. The Ver- 

 mont report suggested two general principles which have been 

 of great service in the further discussion of the nature of meta- 

 morphism and the age of the New England rocks. The first 

 point relates to the distortion and alteration of pebbles in con- 

 glomerates. As far back as 1832 Prof. Hitchcock had noticed 

 the singular alterations in the shapes of pebbles constituting 

 conglomerates in Rhode Island. Not till 1861 was he able to 

 present satisfactory considerations concerning their distortion 

 and alteration. He argued that pressure and metamorphism 

 could totally obliterate the shapes of pebbly constituents and 

 convert them into crystalline schists. Very few of his contem- 

 poraries followed him in this generalization. The large geo- 

 logical manuals of Dana and Le Conte conspicuously avoided 

 any mention of this view. To-day the skilled petrographers 

 of the country unanimously indorse the doctrine of the distor- 

 tion and alteration of the fragmental constituents of sediments. 



So long as our paleontologists referred the Cambrian fossils 



