1891]. Geology and Paleontology. 565 
General Notes. 
GEOLOGY AND PALEONTOLOGY. 
On the Crystalline Schists and Their Relation to the 
Mesozoic Rocks in the Lepontine Alps.'—At the close of the 
year 1888 Prof. T. G. Bonney read before the London Geological 
Society a paper in which he maintained that these rocks could be 
arranged in certain fairly definite groups, which exhibited a strati- 
graphical succession. On this communication only two criticisms of 
importance were offered. Of these one expressed a doubt as to the — 
value of the method which Mr. Bonney had adopted in his work ; t 
other affirmed that certain schists, regarded by Mr. Bonney as members — 
of a very ancient series, probably Archean, had been demonstrated 
by the presence of Mesozoic fossils to be of the latter age; or, in 
other words, that in the Alps ordinary sediments deposited in the 
Jurassic epoch had been subsequently converted into true crystalline 
schists, a result øf metamorphic action, which he had implicitly 
affirmed to be incredible. Early in 1890 Prof. Bonney replied to these 
Criticisms in the following language: i 
‘ The former criticism, which amounted to an assertion that the 
general succession of the Alpine rocks could only be ascertained by 
very detailed mapping, in my opinion indicated an imperfect knowl. 
edge of the subject, while it was scientifically unsound and historically 
incorrect. It indicated an imperfect knowledge because, as a matter 
of fact, a considerable part of the Alps has already been mapped, not 
by irresponsible amateurs but by official surveyors, and it was with the 
interpretation of these maps that I was largely concerned ; and because 
it assumed that an impossibility could be performed. As I have had 
the honor to fill the same position in the Alpine Club that I haye done 
in this society, I may affirm, without fear of contradiction, that a 
very elaborate petrographical mapping of the Alps 1s impossible, for 
the most painstaking and conscientious of surveyors must assume much 
that is incapable of demonstration. A very'large part of the whole 
area is concealed by snow, glaziers, débris, pasture, forest ; and some 
1 On the Crystalline Schists and Their Relation to the Mesozoic Rocks in tDe & — 
Alps. By T. G. Bonney, D.Sc., LL.D., F.R.S., F.GS., Professor of Geology 
sity College, London, and Fellow of St. John’s College, Cambridge. 
