Charles Thomas Jackson. — Wood worth. 73 
It was his method to give strictly scientific as distinguished 
from economic geology in the introduction of his reports. It 
will be worth our while to examine the introduction of the 
Rhode Island report somewhat at length, since the author has 
brought together there some of his concepts of the theory of 
geology. 
It is clear from a perusal of this chapter that he was not 
an advocate of biological methods in geology. His predilection 
for chemistry and mineralogy manifestly made geology for 
hinj a mineralogical rather than i'. stratigraphical science, 
and the ptHUiliarly crystalline character of the rocks of 
New England fostered this view of geology. "It must be 
evident," he states, "to any one conversant with modern geo- 
logical works, that they are frequently very deficient in cor- 
rect mineralogical descriptions of the rocks, while great stress 
is laid upon the accidental fossils, which they contain. Zoo- 
logical and botanical characters are certainly of great value 
and importance, but the}^ are not so decisive, respecting the 
age of a deposit, as the order of superposition of strata and 
the mineralogical composition of the rock itself." We shall 
see presently how he was misled by his reliance upon minera- 
logical characters and through the setting aside of the plain 
evidence of recognizable fossils. But we should judge him in 
tliis matter by the standard of "the forties" when the system of 
Werner had yet its advocates among the highest in the ranks 
of geological science. 
It was in the case of the Rhode Island Carboniferous that 
Dr. Jackson gave way to the prevailing misconception of the 
meaning of metamorphism in its application tc) the problem 
of time. From the fossils contained in the coal measures, he 
inferred that the beds were of fresh-water origin, "either from 
lakes or from the estuar}-^ of some ancient river," an opinion 
which the writer believes abundantl}^ confirmed by the most 
recent studies in this area. He recognized the likeness of the 
flora of these rocks to that of Pennsylvania and Nova Scotia 
and to the Carboniferous plants of New Brunswick, England 
and France, yet he rejected this evidence in fixing the age of 
the beds. "From the fossils alone," he writes, "a geologist 
would class the graywacke rocks of Rhode Island with the 
secondary formations, and make them identical with the coal 
