CLARK: TACONIC REVOLUTION. 147 
In a later paper, Bailey describes two belts of so-called Cam- 
bro-Silurian rocks, one northeast and another southwest of the 
granitic axis in central New Brunswick. 
"We may now turn with profit to consider the belt of rocks 
which, to the west and the southwest of the Benton syenite band, 
intervenes between the latter and the great Silurian tract of 
northern New Brunswick. . . . The only true Cambro-Silurian 
or Ordovician strata are those of the Beccaguimic valley, and 
these, representing the Lower Ordovician, are exposed only over 
a very limited area. 
"If we now pass to the second great belt of slaty rocks in cen- 
tral New Brunswick, viz., that lying south of the great central 
granite axis, we find new light forthcoming here also, but in the 
direction of indicating a more recent rather than a more ancient 
horizon for these strata than had previously been entertained. 
"As in the case of the Carleton county beds, the necessity for a 
change of view arises from the discovery of fossils. Up to the 
time of the presentation of this paper the only organic remains 
observed were certain obscure forms, resembling Dictyophyta, 
found by Mr. W. T. H. Reed, in the slates of Spring Hill brook, 
five miles northwest of Fredericton, and the collections made 
by Chas. Robb and others in the Nashwaak valley. Both of 
these tended to indicate Silurian horizons, the latter even ap- 
proximating to Devonian, yet the great bulk of the strata, con- 
sisting of quartzites and slates, were still regarded and repre- 
sented as Cambro-Silurian. Quite recently, hov/evcr, the writer 
has been fortunate in finding the latter beds also to be not only 
fossiliferous but Silurian, the fossils consisting mainly of grapto- 
lites of the genus Monograptus. From their occurrence at two 
widely separated localities (Murray's brook, seven miles north- 
west of Fredericton, and the shore of the St. John river, opposite 
the mouth of its tributary, the Mactaquac), and the almost 
unvarying character of the strata over the entire district, as 
might be expected in deep water sediments, it seems probable 
that the greater part if not the whole of the area in question 
must now be regarded as Silurian. 
"Thus in each of the great tracts of Pre-Carboniferous rocks 
in central New Brunswick progress towards a more assured view 
of their age is being made. While, however, the country remains 
