404 



DESCRIPTION OF THE COUNTRY BORDERING 



down on the slope or plain lying between the hills and the lake-shore, or in the 

 valleys, their course, as before stated, can still be traced by the eye at a great dis- 

 tance, forming narrow ridges with abrupt sides, concealed in a great measure by 

 the talus at the base of the hills, until they enter the naked escarpment of trap at 

 the top, as shown in the preceding sketch. 



Several narrow dikes often occur in the space of one hundred yards ; and some 

 of them send off lateral intrusions between the slate-beds. On the north side of 

 Pigeon Bay, the annexed section occurs, illustrative of the manner in which the 



ft c 



a. Overlying trap-bed. b, h. Slates, r. Lateral injection of trap. 



slates of this region alternate with trap-beds, and exhibits at the same time a lateral 

 injection from a neighbouring dike. A short distance from this point, are several 

 intrusions of trap from below, through fissures in the slate, one of which does not 

 quite reach the present surface, as shown in the subjoined section. The slates are 

 but slightly disturbed, and then only in the immediate vicinity of the dikes. In 



h n h n I) 



a, a. Trap. /». //. h. plates. 



these same beds are many singular spheroidal concretions, bearing considerable 

 resemblance to septaria. They appear to occupy a certain position in the thinly- 

 laminated slates, as shown in the following section, and are composed of a grayish- 



coloured material, which decomposes easily, and leaves long lines of cavities in the 

 vertical walls of the lake-shore. They resemble in some respects the concretions 

 in the altered slates of Passabika Eiver, but differ from them in the contents of the 

 spheroids. 



A few of the prismatic dikes in this vicinity exhibit the appearance shown in 

 the following sketch by Major Owen. The dike represented is on the lake-shore, 

 and projects ten or twelve inches from the face of the escarpment. About the 

 centre, the prisms are divided by a vertical seam of steatitic material, from two to 

 three inches thick, with thin scales of calcite next the ends of the prisms. Many 

 of the angles of the prisms on different sides of the seam coincide, but, as the greater 



