THE PHYSICAL EVOLUTION OF ACADIA. 
15 
Outside of this, to the north and passing through the south- 
central part of New Brunswick diagonally, is an area of gray 
slates and flags, mostly barren of fossils but having a few grap- 
tolites. This is a Syrtensian or ocean shoal area, similar to 
the ocean shoal area of Lower Huronian time in Nova Scotia, 
it was traversed by cold currents from the northeast which 
brought the graptolites from a more northerly station. 
Finally, extending across the northern part of the province 
is an area of more calcareous and lighter colored slates with 
layers of reef building corals and various genera of brachiopods 
and lamellibranchs. These corals indicate a warmer temperature 
of the sea, and so probably a current setting north-east and 
carrying warm waters from a southern source. 
This contrasted condition of the sediments going northwest- 
ward on the Silurian rocks, reminds one of the succession 
vertically in the St. John terrane, only that the highest division 
of the latter, with its Scandinavian faunas, evidences the con- 
tinued presence of cold ocean waters from the North Atlantic, 
rather than of warm currents from a tropical or warm-temperate 
sea, was found in northern New Brunswick in the Silurian age. 
EXPLANATION OF MAP NO. II. 
The time chosen for representation in this map is the middle 
of the Silurian Time, marked in this region by the deposits of the 
lower third of the terrane. Judging by the absence of strata of this 
age, from all southern Nova Scotia it was then dry land, and was a 
part of the gathering ground whence came the rafts of trees that 
are now found in the Dadoxylon sandstone of New Brunswick. In 
front of this Nova Scotian highland (to the north-west) are the 
deposits of a marsh and lagoon area containing a varied 
land flora of pseudo Carboniferous facies. Northwest of this 
(in the Nerepis Hills) are estuarine beds with Silurian fishes 
and crustaceans and dwarfed brachiopods. East and south-west 
of these we find Silurian littoral animals of several classes. North- 
west of the Nerepis hills is a wide belt of flags and slates with 
a sparse fauna including Monoprionoid graptolites, indicating 
cold ocean waters. This is separated by a ridge of older rocks 
