Prof. Bonney—Crystalline Schists of the Alpune Chain. 505 
THOMSON (J. A.). 1915. No.1. ‘‘Brachiopod Morphology: Types of Folding 
in the Terebratulacea’’: GEOL. MAG., Dec. VI, Vol. II, pp. 71-6. 
—— 1915. No.2. ‘‘Brachiopod Genera: The Position of Shells with 
Magaselliform Loops, and of Shells with Bouchardiform Beak Characters’’ : 
Trans. N.Z. Inst., vol. xlvii, pp. 392-403. 
—— 1915. No.3. ‘‘ Additions to the knowledge of the Recent Brachiopoda 
of New Zealand’’: Trans. N.Z. Inst., vol. xlvii, pp. 404-9. 
1V.—Own tHE Ace oF THE ORYSTALLINE SCHISTS IN THE PIEDMONTESE 
AND OTHER PARTS OF THE ALPINE CHAIN. 
By Professor IT. G. BONNEY, Se.D., F.R.S. 
R. PRELLER’S recent contributions to this Magazine on the 
geology of the Piedmontese Alps prove that (1) Italian 
authorities have expressed widely different opinions on this subject, 
and (2) some of them have maintained sundry Alpine gneisses and 
crystalline schists to be Palzozoic or Mesozoic (often Permian or 
Trias) in age. I infer from these contributions that he is well 
acquainted with the physical geography of this region, but fail to find 
in them any signs of either microscopic study or independent petro- 
logical work. As these have led me in several cases to very different 
results, I shall venture to put them on record as briefly as possible. 
In the course of thirty-five visits I have wandered over the peaks and 
valleys of the Alps from the southern border of the Cottians to the 
Salzkammergut, paying at first much more attention to physical than 
petrological questions. But in 1869, when beginning to lecture on 
geology, I found not only (as I was already aware) that my knowledge 
of rocks was scanty, but also that on this subject very little trust 
could be given to much that had been written. So I tried, as best 
I could, to teach myself.! With this intention I visited many places 
of petrological interest in our own country and on the Continent, 
forming (partly by purchase) a considerable collection of rock 
specimens and slices. Circumstances soon directed my attention 
to the gneisses and crystalline schists, and from 1872 I paid more 
and more attention to them in my Alpine journeys, of which this 
was the thirteenth. In 1885 (my twenty-first journey) I began 
endeavouring to obtain clearer ideas about their succession, history, 
and relation to the ordinary stratified rocks, by running sections, 
sometimes up to, sometimes across the watershed of the chain, going 
in that year from the Lake of Lucerne to the Lago Maggiore and 
returning across the Great St. Bernard. In 1887 I made two other 
complete sections, one from Grenoble to Pinerolo across Dauphiné, the 
other across the Tyrol well to the east of the Brenner Pass, and since 
that date, till the last and thirty-fifth in 1911, each journey has kept 
petrological questions well in view. On looking over a list of my 
geological papers I see that about thirty deal with Alpine petrology, 
and may add that one result of these journeys has been a collection 
1 Sorby, the ‘‘ Father of Microscopie Petrography ’’, had not published much 
on that subject before this date, David Forbes still less, and Samuel Allport 
was only beginning. The ordinary textbooks of geology were either of no 
value or misleading. 
