in the Island of Malta. 129 



2dly^ To illustrate, from a comparison of the two ex- 

 amples some of the peculiarities of the first, and their analogy 

 to the phenomena of glaciers. 



1. Previously to the autumn of 1846, a large quantity of 

 mud, dredged up from the head of the Great Harbour of 

 Valetta, had been deposited on some nearly-level ground, 

 beneath a line of low cliff which originally bounded that part 

 of the harbour, and in the immediate vicinity of a large tank. 

 The mud is of an alluvial character, containing shells and 

 some small stones. From certain indications it would seem, 

 that the mud — either from being so placed originally, or from 

 previous motion — covered nearly the same extent of ground 

 (that is to say about two acres) which it does at present. 

 The slide that I am describing consisted in the flow of the 

 main body of the mud, which was piled up on the right to- 

 wards the sea, over the lower parts on the left. The autumnal 

 rains appear to have thoroughly soaked this mud, previously 

 dry and hard ; and, the tank being full, the superfluous water 

 which was turned off descended over the cliff, and increased 

 the serailiquid state of the deposit.* 



The result appears to have been, that the upper parts of 

 the mud collected in a large heap near the sea descended 

 gradually on the land side, and in some places passed be- 

 yond the original boundary. Six distinct streams, of different 

 sizes, seem to have descended in this manner from the same 

 origin. Their separation appears to have been caused by 

 the difference of resistance and level in the surface of the 

 dry mud over which they flowed. In several places the dark 

 dry mud of the original surface may be seen separating the 

 streams, and may be distinguished on the drawing by its 

 deeper colour. From the elevation of the new streams, these 

 old portions now appear as troughs of irregular form and 

 surface, and are somewhat drawn and contorted by the 

 motion of the streams on either side. In some cases the old 



I 



* So great was the pressure at one place, not included in the drawing, that 

 the adjacent road and wall were pushed fifteen feet into the sea, to the great 

 annoyance of the Government Surveyor, who seems to have had no notion of 

 the locomotive properties of mud. 



VOL. XLVI. NO. XCI. — JAN. 1849. I 



