668 DR. C. CALLAWAY ON THE : [ Nov. 1902, 
It is needless to describe further specimens. ‘That the foregoing, 
especially (461) and (498), are true crystalline schists will not, I 
think, be disputed. Prof. Bonney, in com- 
a 3 Z, menting on the probable origin of these 
54 Gh pats ° ° 5 4 
E ay ie schists, sometimes suggests micro-granite 
ie (@) e . 
an D as an alternative to felsite. I have 
iss) ° . 
3 never seen any mass of micro-granite 
S) 
in Central Anglesey: the granular 
quartzless felsite, so far as I have 
observed, being the only source of the 
schists. However, I must leave the 
elaboration of the details of the schist- 
making process to younger workers. 
Prof. Theodore Groom, D.Sc., has been 
kind enough to relieve my eyesight by 
—= 3 miles. 
SCHIST GRANITE 
SS —Z SLi 
ALLL) 
distance 
A4Tt 
a feo eae examining the water-clear granules of 
> (= ue this series of slides in convergent light, 
RS et z and he permits me to use his diagnoses 
= pics = in the foregoing descriptions. 
iy Es 8 | ) 
> iru & I have not forgotten that the crystalline 
8 ce = limestones included in these schists at 
roe “2- <  Bodwrog and Porth Trecastell may be 
2 S72 & thought to indicate a sedimentary origin. 
a i3< 5 J have long since, however, come to the 
= “>= "S conclusion? that these limestones are 
= pes © > chemical segregations, produced during 
Hy “i % deformation. ‘They are associated with 
~ = | rotten ferruginous schists, intermixed with 
z aan =  quartzose and micaceous bands, and occur 
S lia = in lenticles, varying in dimensions from 
3 ‘2x  .& microscopic films to masses several feet 
3 ™e & thick. I have not been able to work 
= = out in detail the problem of their 
ae 4 genesis; but these facts are clearly in- 
Q . ‘—~ consistent with a sedimentary origin of 
> f the schists, and tend, I think, to confirm 
S LD the view held in this paper. 
ae ix (3) The Granite (Haplite) and 
. WN < Quartz-Felsite. 
aa \S These rocks are intruded into the diorite 
and the felsite after the production of 
their schistosity, as will be shown later 
Yj 
= [AY on. The former have never, I believe, 
z Ne been affected by earth- pressures to a 
=) ne 
br material extent. sk gi 
‘ Rep. Brit. Assoc. 1887 (Manchester) p. 706. 
