Laurentian Rocks. 131 
It is impossible to conceive that the widely varying 
gneisses and their interposed layers of quartzite could have 
resulted from the consolidation of any viscous or semi-solid 
magma, though it is quite possible to imagine these schis- 
tose rocks as having been contorted when softened by heat 
in the presence of salt water and carbonic acid, and even 
melted in part into a viscid granitic magma. 
‘The shearing displacements described above must have 
taken place after the granite had at least partially solidi- 
fied. These movements must have occurred long before the 
dykes of diabase broke through, for they have sharp unal- 
tered walls of gneiss and granite, which at that time were 
so far cooled as to be brittle. 
ReEcENT AURORAL DISPLAYS. 
By Prof. C. H. McLgop, of McGill College. 
The auroral display of the night of February 13th was 
observed throughout the northern portion of North Ame- 
rica, in Britain, and probably throughout northern Kurope. 
_It was without doubt the most brilliant of the auroras 
observed here since 1870. In Montreal, it became visible 
shortly after sunset, and increasing in splendor attained its 
greatest brilliancy at between 7 and 7.30 p.m. Thereafter, 
gradually fading, it appeared as a uniform haze at 8.30, 
and the sky became completely overcast shortly after 
9 o’clock. The most marked feature of this aurora was the 
bright red cone of light having its base between N. and 
N. 60° W., and extending to the zenith. The cone main- 
tained an approximately constant position, and was of a 
uniform bright red colour, changing in tint only as it 
increased to a maximum and faded away. In front of this 
bright red screen there were slowly moving streamers of 
brilliant reds and greenish tints, and these also extended 
at times throughout the whole northern quarter of the sky. 
Low down in the north there was an arch of white light, 
and at one or two points in the N. EH. there were columnar 
patches of coloured aurora which also maintained a fairly 
