66 



SCIENCE-GOSSIP. 



The following is a tabular summary of the 

 Maltese rocks and their equivalents in the Vienna 

 Basin : 



seems as though but a touch is wanting to cause 

 them to break away and to precipitate them 

 into the valleys beneath. Examples of this kind 





Formation. 



Thickness. 



Equivalent 

 Vienna Basin. 



Series. 





I. 



2. 



Quaternary Deposits 

 Upper Coralline Limestone . 



. 250 feet . . 



Leithakalk 



Tortonian \ 





3- 



4- 

 5- 



Greensands 



Clays 



Globigerina Limestone 



50 ,, 



30 ,, 



200 ,, 



GrunderSchichten . 



Schlier 



Horner Schichten . 



Helvetian 

 • Laughian 1 



Miocene 



6. 



Lower Coralline Limestone . 



• 500 „(?). 



Solszka Schichten . . 



Aquitanian . . 



Oligocene 



The deposits thus arranged may be divided into 

 three groups. 



The first is composed of ossiferous breccias and 

 valley drifts, and they are analogous to the 

 Quaternary deposits of Nubia, Algeria, Candia, 

 Sicily and Gibraltar. 



The second comprises the various sub-divisions 

 of the Upper Coralline Limestone, and resembles 

 the Leithakalk of the Vienna Basin. 



The third group is made up of the remaining 

 beds, and answers to the Miocene of Italy, Algeria 

 and Sicily. 



The general dip of the strata is in a north-east 

 and an east-north-east direction ; but in certain 

 localities it has been somewhat affected by faults 

 and other local displacements. In Malta the dip 

 is more pronounced than in Gozo, and, as a result, 

 the contours of the northern coasts of the two 

 islands present some striking contrasts. The 

 strata of Malta shelve off at a low angle towards 

 the north ; and the shores are therefore low-lying 

 and, when viewed from the sea, present a tame 

 and monotonous appearance. 



In Gozo the original horizontality is more or 

 less preserved, and the coast-line there consists of 

 an unbroken series of precipitous cliffs that impart 

 to the shore-line an effect which is both bold and 

 picturesque. These cliffs are composed of Lower 

 Coralline Limestone, and, rising sheer from the 

 water's edge, they tower to a height of between 

 300 and 400 feet above the waters of the Mediter- 

 ranean. From the edges of their summits and 

 falling back in gently undulating curves lie the 

 Globigerina deposits, capped with sombre-coloured 

 clays and golden-hued sandstones; while crowning 

 the whole lay the variegated strata of the Upper 

 Coralline beds, the mural precipices and craggy 

 escarpments of which stand out in bold relief 

 against the clear blue Mediterranean sky. 



The terraced slopes that lie between these upper 

 and lower cliffs offer some remarkable examples of 

 the effects that atmospheric denudation has had 

 upon them. From the escarpments along the hill- 

 sides of the Binjemmas, and from the faces of the 

 sea and the plateaux cliffs, huge masses of partly- 

 detached rocks stand out at varying angles, and so 

 unstable do many of them appear to be, that it 



are very common in both islands ; but the cliffs of 

 Dingli, Emtahleb, Fom-ir-Rih and St. Paul's Bay 

 afford some of the best examples. Strewn along 

 the bases of the escarpments in a state of the 

 wildest confusion lie rock masses of every conceiv- 

 able size and shape, all of which have at some 

 previous time formed a part of the cliffs that now 

 loom hundreds of feet above them. 



Atmospheric agencies have contributed much 

 towards this scene of destruction. Of these, frost 

 probably played an important part during the 

 period when the greater part of Europe was 

 enveloped in a " mer de glace." and when almost 

 Arctic conditions of climate prevailed around the 

 Mediterranean, where temperate and even semi- 

 tropical conditions now exist. But it is to the 

 insidious sirocco and to the action of rain on 

 the clay beds that the greatest amount of the 

 destruction seems to have been due. Their 

 attacks upon the sands and clays that underlie 

 the limestone cliffs have undermined the latter, 

 and have caused the rock to split and roll down 

 the slopes. At Fom-ir-Rih, Ghain Toffiha and 

 Karraba there are examples of areas consisting of 

 several acres that have broken off, and have sunk 

 to lower levels in consequence of the eroding 

 action that the underground springs have had 

 upon their unstable foundations. The south and 

 south-western shores of Malta appear to have been 

 more subject to these landslips than any other part 

 of the islands, a fact that is due to the south- 

 westerly dip of the strata between Carmola and 

 Fom-ir-Rih. The beds in these localities have 

 therefore a tendency to slide along their dip-planes, 

 and hence, when their foundations are weakened, 

 fractures of considerable extent occur. The regu- 

 larity with which these downthrows take place 

 is strikingly shown by the Phoenician cart-tracks 

 that skirt the summits of the southern cliffs. 

 Many of these, after traversing the islands for 

 some distance inland, trend towards the coast, and 

 there break off at the very edge of the cliffs. 



Such are the main geological features of the 

 islands, the appreciation of which are necessary 

 for the understanding of the succeeding details of 

 the subject of these papers. Like all limestone 

 districts, the Maltese strata present many evidences 



