128 Barrande and the Tacomc System — Marcou. 
pens that a science, such for instance as thai of geology, pos- 
sesses a sort of aristocracy, consisting of the most talented, 
learned, active and influential of its devotees. The views of 
this body of men, on any difficult problem that may present 
itself, are usually regarded as conclusive, and are quietly 
adopted by the less distinguished members. Indeed, the opinion 
of any one of these latter, would be scarcely listened to, pro- 
vided it should happen to be contrary to the established creed 
of the dominant party. As a general rule the leading men are 
right, and yet it will sometimes happen that they are wrong. 
One of the most remarkable instances on record, is that of the 
great question in American geology, relating to the age of the 
rocks which Dr. Emmons called the T'aconic si/stem. Upon this 
question nearly all of the leading geologists of North America 
arranged themselves upon one side, and, as it turned out after 
twenty years discussion, on the ivrong side. Although they were 
wrong, yet so overwhelming was the weight of their authority, 
that for nearly a quarter of a century. Dr. Emmons stood al- 
most alone. He had a few followers, but they were not men 
who had made themselves sufficiently conspicuous and influen- 
tial to contend successfully against an opinion that was sup- 
ported by all the great geologists of the continent in one 
compact body. In consequence of this powerful opposition, the 
Taconic theory gradually sank so low in reputation, that it was 
at length considered to be scarcely worthy of the notice of a 
scientific man. 
''During the last thirteen years, a great revolution of opinion 
has occurred with regard to the views of Dr. Emmons. Al- 
though not entirely adopted, they are now considered to be, in 
a general way, well founded. The opposite theory, that all of 
those rocks which he placed in the Taconic system are above 
the Potsdam sandstone, instead of below it, as he maintained, is 
completely exploded. It is at this moment dead, more so than 
was the Taconic theory in 1859, the year in which the subject 
was reopened. As I understand it at present, some of the Ta- 
conic rocks are certainlj' more ancient than the Potsdam, others 
may be of the same age, and perhaps some of them more recent. 
The details are not yet worked out, and judging from the 
manner in which the strata are folded, broken up and thrown 
out of their original position by almost every kind of geological 
