290 



Transactions. — Geology. 



Appendix. 



Extract from the Rev. 0. Fisher's Paper "On the Elevation of Mountains 

 BY Lateral Pressure." (Trans. Cambridge Phiilosopliical Society, XI., 1869.) 



Let us call t the thickness of the crust, which has been thrown into 

 corrugations by the contraction of the subjacent stratum ; and, for the sake of 

 illustration, let us suppose one chain of mountains to be formed across every 

 hundred miles of a great circle. 



Let A B D c, fig, 1, be a vertical section of such a ]:)ortion of the crust 

 before the contraction of the stratum below it. 



AB = 101 miles. A.c = t. eb = 1 mile. 

 Then, owing to the contraction of the stratum below, A b D c will assume some 

 such form as A m b d c, fig. 2, or fig. 3, where A b — 100 miles, and it is clear 

 that the section of the elevated mass M being due to the shortening of the 

 base of the rectangle A D by one mile (if we neglect compression), must be equal 

 to the rectangle E D, i.e., to t square miles. 



If then, as supposed, the crust be 25 miles thick, and, for simplicity's sake, 

 we take an isosceles triangle for the profile of the upraised mountain mass, we 

 shall get an isosceles triangle of 25 square miles on a base of 100 miles, which 

 would give a range of mountains half a mile high. If only 50 miles out of 

 the 100 were disturbed, as in fig. 3, the range would be a mile high, and so on. 

 Such ratios would be rather greater than occur in nature, even allowiug for 

 subsequent denudation, so that the theory seems to be at any rate not deficient 

 in its capability for producing the results attributed to it. 



Art. XLYIII. — Port Nicliolson an Ancient Fresh-water Lake. 



By J. C. Cbawford, F.G.S. 

 [Read before the Wellington Philosopldcal Society, ISth August, 1873.] 

 A REMARK and a question by Dr. Hector have led to the subject of the 

 following observations. The remark was that the peculiar denudation of the 

 Miramar Peninsula was difficult to account for under present conditions, and 

 gave him the idea that it was formerly the summit of a mountain. The 

 question was, whether I had observed any signs of marine remains in this 



