GEOLOGICAL STRUCT Ultli. '20') 



lumps of white limestone, often as large as the fist, 

 heavy, hard, and crystalline. Strings of calca- 

 reous spar were also disseminated through the 

 mass. The pieces, both of lava and limestone, 

 were irregular in shape as well as size ; but some 

 of the lumps of limestone, as well as those of lava, 

 appeared partially rounded by attrition. The pro- 

 portions of the two materials varied in different beds, 

 the limestone sometimes equalling the lava pebbles 

 in quantity, sometimes the lumps of lava greatly 

 predominating over all the other materials. From 

 these rough conglomerates, the beds passed through 

 every gradation into the finest possible tuff. They 

 were all perfectly stratified, forming regular, hard, 

 tough beds, one or two feet in thickness. Their 

 colour varied from a dark yellowish brown, in the 

 eoarser parts, to a light stone or dove-colour in the 

 more finely grained portions. 



In the island of Macr these beds have a regu- 

 larly quaquaversal dip from the centre of the island 

 to the sea, on the north, west, and south sides of it. 

 On the south-west side they were inclined at an 

 angle of full G0° from the top of the island to its 

 base. The upper ends of these beds form a curvili- 

 near ridge, concave towards the interior of the 

 island, where is another hill, of a conical form, the 

 composition of which I was not able to ascertain. 



Of the structure of Do war I can only say that 

 it is formed of beds of precisely the same appear- 

 ance as those of Maer, that they arc inclined at 



