11.(1 



opportunity of making upon its general character and position, 

 with reference to the present line of the coast near Pernainbuco, 

 I had arrived at the conclusion, that instead of having been 

 " either a bar elevated" or " a sandstone rock worn away," 

 it was once the line of the shore itself, principally from the 

 peculiar form and angle at which it lies as shown in diagram 

 No. 1 ; and that this, by some cause or other which I shall 

 not now attempt to explain, has become indurated, and the 

 sea has then worked in behind it and washed away the loose 

 soil, until it formed a new and its present line of coast. 

 In this opinion I was fully confirmed when I reached Bahia 

 and found within the point of the bay, and near the English 

 burying ground, a beach composed of sand and loose granitic 

 or sienitic shingle, and close to it large portions of the reef 

 in situ, covered with similar rounded pebbles or shingle in- 

 durated into a compact mass, resembling the present beach in 

 all respects except its loose and rolling character. The figures 

 Nos. 1 and 3, in plate No. 2, represent a section of the part in 

 question, the pebbles or boulders of sienite were so closely 

 united to the sandstone beneath them that they could hardly be 

 detached ; and I found many specimens similar to that now 

 presented, which is a rounded pebble, one half of sienite and 

 the other of sandstone consolidated to a degree of hardness 

 equal to that of the sienite itself. Fig. 1 of the 2nd diagram 

 represents one of several fragments of the reef which, though 

 nearly destroyed by the action of the waves, still stand erect — 

 the more refractory boulders resisting destruction better than 

 the sandy substratum — so that they are worn somewhat into the 

 shape of mushrooms. Tig. 2, plate 2, represents the reef near 

 Bahia, outside the Bay, at about a mde from the point ; it is 

 there about seventy or eighty yards wide, though from the cir- 

 cumstance of having been a good deal worked, for the purpose 

 of obtaining building stone, it is rather difficult to speak with 

 accuracy, The material of the reef is here exceedingly com- 

 pact, as you will observe from the fragment presented. 



