518 W. F. Stanley— On Glacial Periods. 



the present meeting some advance would be made in solving this 

 great problem, as well as in correlating and arranging the glacial 

 beds of Canada, Acadia, and Britain. 



18. — On the Occurrence of the Norwegian ' Apatitbrtnger ' 

 IN Canada, with a Few Notes on the Microscopic Characters 

 of some Laurentian Ajviphibolites. 



By Frank D. Adams, M. Ap. Sc, Assistant- Chemist and Lithologist to the 

 Geological Survey of Canada. 



THE paper first gives a short account of the investigations which 

 have been made on this amphibole-scapolite rock in Norway, 

 where all the principal deposits of apatite either traverse it, or occur 

 in its immediate vicinity. The deposits of apatite in Canada gene- 

 rally occur associated with some variety of highly pyroxenic rock, 

 often holding orthoclase and quartz. 



The ' Apatitbringer ' has, however, recently been found in the 

 vicinity of the town of Arnprior on the river Ottawa. It closely 

 resembles the Norwegian rock, both in external appearance and in 

 its microscopic characters, containing hornblende, scapolite, and 

 pyroxene as essential constituents. A number of amphibolites in 

 the museum of the Geological Survey of Canada, which resemble 

 this rock in appearance, have been sliced and examined with the 

 microscope, and one of them found to contain scapolite in large 

 amount. It was collected at Mazinaw Lake, in the township of 

 Abinger, and is from the same belt of hornblendic rocks as that in 

 which Arnprior is situated. The paper closes with a short account 

 ♦ of some of these amphibolites. 



19. — Upon the Improbability of the Theory that Former 

 Glacial Periods in the Northern Hemisphere were due 

 TO Eccentricity of the Earth's Orbit, and to its Winter 

 Perihelion in the North. 



By W. F. Stanley, F.G.S., F.R. Met. Soc. 

 TT^HE theory of Dr. Croll, accepted by many geologists, is that 

 I former glacial periods in the Northern hemisphere were due to 

 greater eccentricity of the earth's oi'bit, and to this hemisphere being 

 at the time of glaciation in winter perihelion. This theory is sup- 

 ported upon conditions that are stated to rule approximately at the 

 present time in the Southern hemisphere, which is assumed to be 

 the colder. Recent researches by Ferrel and Dr. Hann, with the aid 

 of temperature observations taken by the recent Transit of Venus 

 expeditions, have shown that the mean temperature of the Southern 

 hemisphere is equal to, if not higher than, tlie Northern, the propor- 

 tions being 15-4 Southern, lo-3 Northern. The conditions that rule 

 in the South at the present time are a limited frozen area about the 

 South Pole, not exceeding the sixtieth parallel of latitude ; whereas 

 in the North frozen ground in certain districts, as in Siberia and 

 North-Western Canada, extends beyond the fiftieth parallel ; there- 

 fore by comj)arison the North, as regards the latitude in which Great 



