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south flank of Mt. Ste. Anne, then passing behind that 

 mountain, rising to greater heights and forming the broken 

 range known as White mountain, which almost encircles 

 and isolates Mt. Ste. Anne, approaching sea level at Corner- 

 of-the-Beach on Mai bay. A fault-bounded outlier of this 

 rock may be seen in a white cliff on the sea front beyond 

 the Murailles, where it lies at an angle against the Bona- 

 venture beds beyond. Much remains to be learned of the 

 fauna of this extensive belt of limestones. 



GEOLOGICAL RELATIONS. 



The foregoing account of the leading topographical 

 and geological features has intimated the geological 

 history of Perce. The steeply tilted older strata present the 

 seaward end of an Appalachian fold of great magnitude, 

 which has been variously broken down. The uniformity of 

 the inclination in the steep fold is expressed by the coin- 

 cident dip of all the older beds, 8o°-85°SE., and this fold, 

 steeply inclined to the north, involves beds from (Cambrian) 

 Lower Ordovician into upper Lower Devonian. 



The construction of the tectonic changes here is compli- 

 cated, perhaps not altogether clear, but the secondary 

 movements expressed by dislocations of the strata are of 

 two orders in time. Of the older faultings there are unlike 

 orders in magnitude. The great Perce fold, exposed only 

 at its sea edge, may be construed as typically Appalachian 

 in its thrust northward. It was an earlier fold than those 

 to the north of it, and was not thrust against a horst of 

 crystallines. The over-tipped Silurian and Ordovician 

 strata present in the Mount Joli section and repeated 2 miles 

 south at Cap Blanc, indicate a profound displacement along 

 the thrust plane after folding which carried southward the 

 inverted succession of the strata; a displacement which 

 would involve the conception of gravitational movement 

 backward (south) along the plane of thrust; a conception 

 apparently reasonable, and squaring with carefully repeated 

 tests. The lesser displacements involved in the down- 

 breaking of the Perce fold are indicated on the accompany- 

 ing map in which those of earlier age are marked 

 by single lines, and those visibly affecting the Bonaventure 

 formation only, by double lines, in both instances dotted 

 where the break is uncertain. Perce Rock is evidently 

 bounded on its long sides by faults which have isolated 



