I58 NEW YORK STATE MUSEUM 



quadratic mass of this continental deposit. The bounding walls are 

 so abrupt, and so brilliant as well, as to make an extraordinary type 

 of mountain scenery which is not comparable in its effect to any- 

 thing known to the writer. To the casual observer this isolated 

 quadratic mass with its high walls is naturally interpreted as a 

 residual block left behind by the faulting away of its lateral parts. 

 I think that this is probably an approximate explanation, but not 

 a final one. The faulting has taken place in the sense that there 

 has been a removal of the outlying portions along approximately 

 vertical planes and probably along corresponding vertical joint 

 faces, but the causes of this removal are, I think, not due to the 

 thrusts generally effective in the process of faulting but to the 

 downsinking of these lateral parts through the removal of the basal 

 calcareous pavement by solution. This fact comes into rather clear 

 evidence on a consideration of the outlying region. This is a part 

 of the tremendous limestone region of Gaspe where practically all 

 the vast Ordovicic and Siluric strata, with a thickness of probably 

 not less than 10,000 feet, and the superjacent calcareous Devonic 

 strata not only reach the coast but run far out to form the coastal 

 shelf. The solution and destruction of this calcareous mass on the 

 sea front is obvious on every hand, particularly in the ragged lime- 

 stone cliffs and islands which bound the coast. 



It is on this open shore, where the sea has cleared away obstruc- 

 tions and long ages of its activity have worked the greatest decay 

 upon the limestone pavement, that the process of the rifting of this 

 Bonaventure plateau becomes most apparent. The sea face of this 

 plateau — Mt Ste Anne — is sheer and in' the line of its normal, out 

 into the sea, lie (1) the joint or rift block, called Petite Ste Anne, 

 which has settled down close to the foot of the parent mass and 

 from which it is today separated by a rift only a few rods wide : 

 (2) the Robin reefs whose tops are exposed at low water some 100 

 rods from the shore; (3) Bonaventure island, 3 miles away, itself 

 a great joint-block with its higher edge to the eastern sea, its lower 

 to the mainland, its surface slope thus from east downward to the 

 west. 



It is not to be bluntly stated that this joint-block o\ Bonaventure 

 island was actually rifted from the face of the residual plateau, as 

 though first in the order of visible remnants, and slipped to its 

 distorted position along the decaying limestone base on which it 

 rests; it is implied that some such process has been in effect; that 



the Bonaventure block has actually been displaced and dislodged 

 from its original place with just the same degree oi certainty as that 



