in the Island of Malta. 131 



scent is not particularly steep, mud which has been very wet 

 will be found the smoothest and least cracked. 



The curved bands appear to be most completely developed 

 in an intermediate interval between the origin and the termi- 

 nation, and also to be widest at that part. An increase in 

 the inclination of the stream appears to break up the curved 

 bands and cause them to become confused, and separated 

 into narrower bands, as at d, No. 3, in the drawing. 



I regret that it was not in my power to procure transverse 

 and longitudinal sections of any of the streams, so as to 

 show the internal structure, and determine whether the dis- 

 tinction of rough and smooth bands obtains to any extent 

 below the surface. 



2. It is proposed, in the second place, from a comparison 

 of the example which has just been described with another 

 mud-slide, to illustrate the peculiarities observable in the 

 drawing, and their analogy to the phenomena of glaciers. 



The first and main peculiarity which I would observe is 

 the existence of curved bands of rough and smooth mud 

 alternating. 



In the spring of the present year, I had an opportunity of 

 examining another mud-slide, also on the borders of the 

 Great Harbour of Valetta, but of smaller size, and in a dif- 

 ferent stage of development. In this case the moisture must 

 have been derived almost exclusively from the rain, and not 

 as in the other instance, from the auxiliary overflow of a 

 tank. In the first slide the surface of the mud formed a con- 

 tinuous slope, and was not raised in ridges ; the rough bands 

 were very slightly higher than the smooth ones. In the 

 second case there were the same bands of rough and smooth 

 mud (much less defined, it is true, but still apparent), but 

 here the rough bands were raised a foot and a half or two 

 feet, so as to form ridges, waves, or wrinkles, swelling 

 and falling over. This evidently resulted from the manner 

 in which the mud had flowed, and the experiments which 

 have been made upon viscous fluids seem to shew the occur- 

 rence of similar wrinkles, except that they are less regular 

 and distinct. I do not, however, pretend to explain how 



