Charles Thomas Jackson. — Woodicorlh. 77 
puny at about this period of their careers, we shall find them 
shortly engaged in succession in the same geological field : and 
however much they may have differed eventually in opinion, 
it is worthy of remark that Jackson chose Whitney to be his 
first official assistant in his geological surveys. 
The four years from 1839 to 1843 were given to this survey, 
the final report appearing in 1841. Annual reports were made, 
the form of which is preserved in the final monograph. The 
title of this work bears the characteristic of the author's aim 
in the added words "with contributions towards the improve- 
ment of agriculture and metallurgy." The introductorjr chap- 
ter is, like that of the Rhode Island report, interesting read- 
ing to the student of American geology. In it Jackson frees 
himself from the details of minerals and rocks as such and the 
localities in which they occur, in order to discourse upon the 
principles of geology, its nomenclature, and upon the relation 
of the rocks of New Hampshire to the standards of the Euro- 
pean column. 
Neither at this early period nor later in his writings does he 
appear to have become involved in the intricacies, either pro 
or con, of the Taconic question. This is probably for the ge- 
ographic reason that his field of investigation lay mainly to 
the eastward of the area studied by Ebenezer Emmons. Yet 
Emmons found his Taconic system in Rhode Island and 
also in Maine. From the latter state, he describes Nereites 
jacksoni, "a name," he states, "conferred from respect to my 
esteemed friend. Dr. C. T. Jackson." It appears also that 
Jackson in later years, as at the time his field work was done, 
was not interested in questions of chronology. 
With singular conservatism, he retains in bold type in the 
New Hampshire report, the Wernerian "Transition" group as 
the best term in iiis opinion for rocks denominated Cambrian 
and Silurian by Sedgwick and Murchison. Yet there is noth- 
ing of intolerance or a wish to suppress their views. He gives 
their names place in the text and protests against their use 
rather than refuses to employ them. He strengthens his ar- 
guments advanced in the Rhode Island report, and remarks 
"that we must regard these terms as merely provisional ; 
for we cannot discover any relationship between rocks formed 
ages anterior to the creation of map, and the tribes who in com- 
