CLARK: TACONIC REVOLUTION. 143 
lowing them along the precipitous face of the mountain, they 
are found to fold over and exhibit a dip N. 40° W. < 40°. They 
are also broken by a fault." 
Again, on page 36M: "The rocks which immediately suc- 
ceed the Pointe aux Trembles, Tuladi and Squatook sandstones, 
referred to the Niagara formation, are the dark grey bluish- 
weathering and more or less calcareous slates which occupy the 
whole of the southern part of Lake Temiscouata. . . . The 
position of these slates in the Silurian system has not been cer- 
tainly determined. At no point has their actual contact with 
the Pointe aux Trembles sandstones been observed, and though 
appearing to dip off from these, and conformably so (S. 65° E. 
<^70°), they are everywhere so extensively crumpled that but 
little reliance can be placed upon their attitude. . . . The gen- 
eral aspect of these fossils [such poorly preserved fossils as occur 
in these slates], however, is that of the Lower Helderberg group." 
It seems that, while there is much more reason for calling these 
slates Silurian than there is for calling those on the north side of 
Lake Temiscouata Ordovician, it does not appear that the so- 
called Ordovician slates have undergone longer or more intense 
folding. 
Logan, in his account of these rocks, gave a section of them 
which was not as full nor as detailed as the one just cited. A 
justifiable misapprehension as to the attitude of the rocks as a 
whole has grown out of the fact that in the paragraph succeeding 
the section, Logan said: "The dip of these strata is S. 50° E. 
<^13°."^ Many writers^ have interpreted this as the uniform 
dip of the whole series, and according to this interpretation, the 
Ordovician rocks are crumpled, while the Silurian rocks are 
j)ractically undisturbed, and the inferred unconformity becomes 
almost a certainty. A glance at the section as given on page 142 
above shows that the dip given by Logan was meant to refer 
to the uppermost beds only, no figures being given by him for 
the underlying strata of the section. These, as given by Bailey 
and Mclnnes, show that the dip, while it is generally directed 
toward the east, varies from 13° to 70°. 
'Logan, Sir William. Geology of Canada, p. 421, 1863. 
*e.g., Bailey, L. W. Proo. Roy. Soc. Canada, vol. 4. sect. 4. p. 39. 1887. 
