BY THE REV. J. E. TENISON-WOODS, F.G.S., ctc. 705 



Before proceeding to the consideration of the interior of the 

 great crater it is desiraUe to summarize the evidence which is 

 afforded us by a study of the geology of the island. First of all 

 it will be observed that there are two lines of volcanic fissures, 

 made manifest by the shape of the island and the dispositions of 

 the craters. The first is from south-west to north-east, beginning 

 with the extinct crater of Binintiang Munti, and ending at the 

 north-east cape of Pirac Piraso. Along this line, which passes 

 through the highest portion of the central volcano and the most of 

 its extinct craters, we have a line of ancient craters, which from 

 their appearance would lead one to believe that they are also the 

 oldest of the island. These are Binintiang Munti, Saluyan, Tabaro 

 and (omitting now the central craters) Pinag Ulbuan, Ragatan, 

 and the islands in the Seno de Hog Hog, which appeared to me to 

 be very much like the remains of an ancient crater. 



At almost risht angles to this line of tissure there is another 

 line, which would take in Las Canas, Balantoc, and the cone of 

 Binintiang Malaki on the north-west. The second line of fissure 

 would appear to be of a more modern character. I think a careful 

 study of the volcanic evidences here exposed must throw some 

 light on the chronology of these different basins, and possibly also 

 upon the great question as to whether there has been a large 

 subsidence where the present laguna now stands. It should be 

 remarked that the greatest diameter of the lake corresponds nearly 

 with the first described line of fissure, and also with the greatest 

 prolongation of the volcanic tufas and trap-i'ocks. 



Interior of the Great Crater. — I now proceed to describe the 

 features of the great centre of activity in this island. First of 

 all I shall give the impressions made upon my mind by a first view 

 from the brink. The effect was certainly very wonderful and 

 startling, so different indeed from anything I had ever seen before 

 that it amazed me with most bewildering sensations. The first 

 thing that strikes one, of course, is the source and origin of all the 

 clouds of white fumes which are always rolling upwards out of 

 the crater, and make it so conspicuous wherever seen. These vents 



