Watts and Newton — Rocks from Solomon Islands. 36 L 



At Bili village and on the south coast of New Georgia (F. 296) 

 tufaeeous limestones occasionally occur on the face of the cliffs. 

 They are of spongy texture, and are evidently the result of springs 

 percolating through coral rock and other calcareous deposits. Under 

 the microscope they show the usual handed structure due to the 

 deposit of minute calcite crystals. 



At the western end of Tetapari Island (F. 304) was found a 

 deposit of volcanic mud devoid of calcareous matter. Very little of 

 this specimen is soluble in acid, and what is left is like the residue 

 left on acting on the foraminiferal mud of the same island with acid. 

 It is evidently a volcanic mud which happens to be almost devoid of 

 organisms, either from the loss of them by solution, or more likely, 

 as the rock is fairly compact, from the circumstances of its deposition. 



On a hill summit, about a mile inland, on Ugi Island, Lieut. 

 Waugh found a curious rotten-stone (F. 302). Fragments of coral 

 showing structure were found in the same locality, so that the rock 

 is almost certainly the result of the operation of solution on a 

 foraminiferous mud like that already described in this note and like 

 those described by .Guppy in this island. The rock is cavernous, 

 the hollows revealing the shapes of dissolved foraminifera. Very 

 little of it is soluble in acid, and the residue consists of fine clay with 

 a few chips of volcanic minerals, such as felspar, augite, and olivine. 

 Mr. Newton remarks that "In one instance a foraminifer was itself 

 preserved in some material which was not affected by acid." 



Two examples of siliceous deposits were found — one in Florida 

 Island, about 20 feet above high water-level (F. 280), and one on 

 Gavutu Island, just opposite, at 10 feet above the same datum 

 (F. 285). They are white or cream-coloured, banded rocks, rough 

 and siliceous in feel, light in weight, and with one or two coarser 

 layers which contain a preponderance of chips of volcanic minerals 

 that are present in some quantity throughout the rock ; these 

 minerals include felspar, augite, hornblende, and olivine, with a 

 little quartz. I append Mr. Newton's full description — 



" A fine-grained, friable rock, which does not effervesce with acid, 

 was examined both in section (F. 280) and also as a powder. 

 Under the microscope it was found to contain numerous organic 

 remains, chiefly the spicules of tetractinellid sponges, and these of 

 many different forms, with fragments which indicate the presence of 

 radiolaria. No foraminifera were detected. 



" F. 285 is another specimen of a very similar rock. Like the 

 last, it did not effervesce with acid, and under the microscope very 

 few organisms could be found ; but those that were present were 

 similar sponge spicules and possibly radiolaria. 



" It will be evident that the conditions under which these two 

 rocks were formed were quite unlike those necessary for the formation 

 of the coral rocks, and they may possibly indicate somewhat deeper 

 water. The deep-sea clay mentioned by Guppy l is quite unlike 

 these specimens, for that is somewhat calcareous and contains but 

 few sponge spicules." 



1 Trans. Roy. Soc. Edin., vol. xxxii, p. 558. 



