John H. Coolie — Black Limestones of Malta. 361 



lare. And the upper, which rests immediately on the coal, contains : 

 Ehynchonella pleurodon, var., Fenestella plebeia, Encrinites, etc. Here 

 the interpretation of conditions would naturally be deepish water 

 for the lower limestone, a change to shallower for the shale, and 

 after the deposition of the underclay and coal a return to such 

 deepish water for the upper limestone. 



Y. — On the Occukkence of a Black Limestone in the Strata 

 OF the Maltese Islands. 



By John H. Cooke, F.G.S., etc. 



WHILE engaged in the examination of the superficial deposits 

 of the Maltese Islands, I have often met with rounded pebbles 

 and angular fragments of a black, crystalline limestone, either lying 

 on the rock surfaces, or embedded in the Quaternary formations. 



The late Professor Leith Adams drew attention to the same fact as 

 long ago as 1867, and in a paper which was published in the Quart. 

 Journ. Geol. Soc. he expressed an opinion that the fragments which 

 he had seen lying on the surfaces of the sides and summits of the 

 Gozitan Hills, belonged to a formation that was of a much later age 

 than any of the rocks that are now to be found in situ in the islands.^ 



Dr. John Murray, too, notes in his brochure'^ on the Maltese 

 Islands the occurrence of similar fragments in the neighbourhood of 

 Marsa Scirocco, and he further adds that no evidences of the rock 

 having been found in situ in the islands had hitherto been recorded. 

 The remarks of these gentlemen led me to consider the matter 

 attentively, and I have, during the last year, been carrying on 

 investigations with the object of discovering the origin of the black 

 marble, the result of which has been to show that it is but a variety 

 of the Lower Coralline Limestone, the basement bed of the Maltese 

 series, and that it occurs extensively in situ in that formation. In the 

 eastern and south-eastern parts of Malta considerable quantities of 

 rounded boulders and angular fragments of black limestone, that 

 vary in size from a walnut to a medium-sized pumpkin occur in 

 the beds of the gorges, in the soil of the fields, and in all those 

 localities where the Globigerina limestone has been eroded away, 

 and the underlying basement rock has been exposed to view. 



In the Quaternary strata, too, of both Malta and Gozo these 

 fragments are especially numerous. The elephant bed in the Benhisa 

 Creek at the south-eastern extremity of Malta affords a characteristic 

 example of their mode of occurrence in the diluvial beds of the 

 island. 



In this bed large water-worn boulders, having, when broken, a 



^ Dr. Adams says, " Indications of more recent beds are seen in the blocks of 

 weathered limestone known as Gozo marble which are seen strewing the valley east- 

 ward of the lighthouse on the northern shore, and in fragments of a black limestone 

 or marble which strew the sides and summits of the Gozo Hills. There can, I 

 believe, be no doubt that these fragments have no connexion whatever with any of 

 the recent formations in the islands." 



- ''The Maltese Islands, with special reference to their Geological Structure," 

 Scottish Geol. Mag. September, 1890. 



