410 Canadian Record of Science. 
that still another such area exists near the mouth of the 
Shiktehawk. In the State of Maine, the three groups of 
strata described are still more clearly represented, for while 
there, as in the province, the slates are the most commonly 
occurring rocks, comprising all the country drained by the 
upper St. John, as well as large areas about Presquile 
and Houlton, we have, in the Fish River Lakes, and again 
at Ashland, beds of limestone, abounding in fossils which 
are nearly parallel with those of Mount Wissick, while 
finally, in the valley of the Aroostook and covering large 
areas, are conglomerates and sandstones, which are the 
evident continuation of those of the Siegas River, presenting 
precisely similar characters and associations, and carrying 
the same fossils. In northern Maine, however, there are 
with these undoubted Silurian strata, great masses of 
volcanic rock, felsites, quartz-porphyries and amygdaloids, 
as well as fine silicious slates and purple micaceous and 
eneissic sandstones, the relations of which are not yet fully 
known. Beds of Devonian (Oriskany) age also occur, as 
they do both in New Brunswick and in the Gaspé peninsula, 
but are much less widely distributed than has been 
previously supposed. Finally, the slates are at a few points 
unconformably covered by bright red sandstones and con- 
glomerates similar to those of the Tobique valley in New 
Brunswick, and the Bonaventure district of Quebec, which 
are referable to the Lower Carboniferous formation. 
Thus the succession of events indicated by the rocks in 
the early history of the region under discussion would 
appear to be as follows. The great period of upheaval, 
mountain-making and metamorphism which brought 
Archaean time to a close, having served to determine and 
to some extent to limit the great St. Lawrence or Acadian 
basin, by lifting above the sea the ridges which still border 
it,—the Laurentides north of the St. Lawrence valley, 
ridges of similar rock along the New England coast, some 
of our own southern hills and similarly some of those of 
Nova Scotia, Cape Breton and Newfoundland—we find in 
the Cambrian and Cambro-Silurian periods which succeed, 
