CALCAREOUS FORMATIONS OF THE SOLOMON GROUP. 571 



degradation of the surface which these calcareous districts undergo during a 

 heavy fall of rain, of as much as 2 to 3 inches in the same number of 

 hours, I have been a frequent witness. In a few minutes the whole hill-slope 

 discharges a continuous sheet of muddy water, the rivulets swell to turbid 

 streams, and the water rushes down the permanent courses with the roar of a 

 mountain torrent. After the rain-storm has passed away, the band of muddy 

 water that fringes the whole length of coast, to a distance of one-quarter or 

 one-third of a mile from the shore, indicates the loss of material which the land 

 surface has sustained. 



The bedded Foraminiferous deposit that forms the mass of the neighbouring 

 island of Ugi is rarely represented among the coast formations of St 

 Christoval. I came upon it only once in position exposed in the banks of a 

 stream near the coast.* The coral rock and the fawn-coloured limestone here 

 appear as a rule to rest directly on the volcanic rock. Occasionally in different 

 parts of the coast I found a coarsely grained deposit composed of the water- 

 worn debris of volcanic and coral rocks with a few shells imbedded. 



The Florida Sub-Geoup. 



From the few traverses which I made in this sub-group I learned that the 

 western islands are more of volcanic formation, whilst the large island on the 

 east side of the narrow passage which bisects the main mass of land is composed 

 on the surface largely of recent calcareous formations. It is to this eastern 

 island that I will restrict my remarks. Traversing it in a S.W. direction from 

 the vicinity of Mboli Harbour to the village of Gaeta, I found an argillite and 

 a dark trap-rock scantily exposed in the lower hill-slorjes. At a height of 500 

 feet a grained limestone associated with a limestone conglomerate appeared 

 at the surface. The coral limestone occurred at an elevation of 600 feet above 

 the sea, and formed the surface up to rather over 900 feet — the greatest 

 elevation I attained. In one locality it displayed a joint-structure. Descending 

 on the other side of the range, the grained limestone occurred at the same 

 height, and I traced these -calcareous formations down to about 200 feet above 

 the sea. In the vicinity of the village of Gaeta, which is elevated rather over 

 100 feet, a volcanic rock appeared at the surface and was exposed in the bed 

 of a neighbouring stream. 



I subsequently made an excursion into the interior of the island for a 

 distance of between two and three miles N.N.E. from Gaeta. I traversed a 

 region of coral limestone gradually rising until an elevation of about 350 feet 



* A similar rock, but sparingly Foraminiferous, occurs on the slopes of Cape Keibeck at an eleva- 

 tion of 500 feet above the sea. 



