BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 
VOL. 9, PP. 163-172, PL: 11 FEBRUARY 10, 1898 
NODULAR GRANITE FROM PINE LAKE, ONTARIO 
BY FRANK D. ADAMS 
(Read before the Society December 30, 1897) 
CONTENTS 
Page 
ILAGROGUCHION, 35 é5n0e aCe COREE TEE EE RmE Oc e conor anno corte ennc Ieee 163 
Generalidescriptionyof the occurrence s...- 4.44) sss cee nes ee sec ee 163 
Microscopical character of the enclosing granite .................--...-.205- 166 
Mierascopicalcharacter on the modules)... s-mssseen eee. a o2s-6 oss ods 167 
Chemical composition of the granite and of the nodules..................... 169 
Onicimtotihe modular structures... 7... 1.0. cs sere eels es Qe feeicle sien Se hcitetans 170 
INTRODUCTION 
While engaged during the past summer in carrying out some work for 
the Geological Survey of Canada in the eastern portion of the province 
of Ontario, a somewhat remarkable occurrence of orbicular or nodular 
granite was met in the township of Cardiff, in the county of Peterborough, 
which, on account of some peculiarities it presents, seemed worthy of de- 
tailed study. 
This part of eastern Ontario is underlain by rocks of Laurentian age, 
which here consist chiefly of crystalline limestones with rusty weather- 
ing gneisses and amphibolites, broken through by great intrusions of 
granite, the geological relations being very complicated and intricate, as 
the mapping of the area now in progress shows. 
GENERAL DESCRIPTION OF THE OCCURRENCE 
About halfway across the township of Cardiff and near its southern 
limits is Pine lake, a body of water some two miles long and averaging 
about a quarter of a mile in width. The bold rocky shores of the lake 
are formed of a rather fine grained reddish granite, except at the northern 
and near the southern extremity, where the granite is associated with a 
dark gabbro-like amphibolite, through which it apparently cuts. The 
granite is in many places quite massive, but usually shows a somewhat 
eneissic structure, marked chiefly by the presence of small and ill defined 
XXIV—Butx1. Guon. Soc. Am., Vor. 9, 1897 (163) 
