354 Methoch otStratigrap/iy. — Whichell. 
tion, as in the "igneous rocks" of the expanded Huronian, 
but massive, crystalline, and in the form of unmodified over- 
flows. 
The new departure necensari/. W/i>/f It will have been 
observed, already, that the complications that arose from the 
promulgation and acceptance of the idea of the Huronian as 
entertained b}^ the majority of geologists up to a very recent 
date, rendered it necessary to revise de novo the classification 
in vogue. It is to the late lamented Prof. Irving, that we owe 
the initiative in this direction, so far as it pertained to a re-ex- 
amination of the type region, although the studies of the 
writer, led him in 1884'^ to call attention to the confusion 
that existed. In this re-examination of the work of Logan in 
the stratigraphy of the oldest rocks, we are impressed with the 
essential correctness of his original conception of the Huron- 
ian formation, and w^e think it is no more than justice to an 
early pioneer in American geology to call attention to it, and 
to vindicate his work from the errors that appear to have been 
fastened on it by the Canadian geologists and by those in the 
United States that have followed them. 
T/ie methods of the new departure. The methods of work 
that geologists in the United States are no\x employing on 
the older rocks are markedly different from those resorted to 
by Logan, and his assistant, Alexander Murray ; and in so far 
as the methods are improved are the results more reliable. 
The early geological work in America consisted largely of to- 
pographic description, and sketch-mapping. The nature and 
distribution of the rock-terraces could not be minutely worked 
out. Not only was the time allowed for such work not suffi- 
cient (nor the money), but the microscopic examination of 
the intimate structure of the different rocks was almost un- 
known as a geological adjunct. With the lapse of time, and 
the increased appreciation of geological surveys, the public 
authorities have granted more time, means, apparatus and 
general co-operation. Much of the early w^ork has to be re- 
viewed. New surveys are made where the first had been pro- 
nounced "finished." While it is necessary to go again over 
much of the early work, it is necessary to treat it with strict 
justice, and in doing so we have to be guided by the publish- 
Address ])efore Section E., A. A. A. S. Pliiladolpliia, 18S4. 
