1894. | NEW YORK ACADEMY OF SCIENCES. 203 
southern New Brunswick, is still doubtful; they seem to be 
wanting at St. John. 
The writer has much pleasure in acknowledging his great 
indebtedness to Prof. Kemp for advice and assistance through- 
out the preparation of this paper; likewise to Mr. G. F. 
Matthew for much inforniation concerning the field geology 
about St. John. It is intended in a future paper to discuss the 
character of the surface-voleanic and other rocks forming the 
Huronian of southern New Brunswick; a series which, in spite 
of the extended and careful work done on it in past years, still 
affords an important subject for microscopic research. 
SUMMARY. 
The so-called Lower Laurentian near St. John, N. B.,is found 
to consist in large part of intrusive rocks, which are of two 
types : 
1. Granite-diorite, typically a tonalite, but varying from 
hornblende-granitite to quartz-diorite. It contains zonal por- 
phyritice cry ‘stals of orthoclase in varying amount, and lies in a 
number of parallel bands, covering a considerable area, and be- 
lieved to be all parts of the same intruded magma, From the 
limited contact effects and other evidence, it is conjectured that 
this magma contained less water than is usual with granitic in- 
trusions. The age of the granite-diorite is uncertain; it is later 
than the Upper Laurentian limestones, and may be Devonian, 
but is probably Pre-Cambrian. 
Olivine-gabbro. Two or three small knobs of this rock, 
varying much in mineral composition, occur near St. John. 
Around the olivine crystals occur remarkably fine reaction rims, 
composed of an inner zone of hypersthene and an outer one of 
actinolite and spinel. The inner zone is considered original, the 
outer one secondary. The succession of Pre-Cambrian forma- 
tion, as provisionally arranged, furnishes a surprisingly close 
parallel to that of the main Archzean continental nucleus, though 
the rocks are not nearly as much altered. 
GEOLOGICAL LABORATORY, COLUMBIA COLLEGE. 
The paper was discussed by Prof. Kemp. 
The Secretary mentioned that the Section had been in ex- 
istence a year and a half and had not had an election of officers 
since the initial organization. It was accordingly moved and 
carried, that the same officers, to wit, Prof. Whitfield, Chair- 
man,and Prof. Kemp, Secretary, be elected for another year. 
