i6o The Irish Naturalist [June, 



We see no reason to doubt the correctness of the accepted 

 view, which regards a peat bog as consisting of a fluid interior, 

 more or less viscous, and an outer felted crust. The closing 

 up of drains and canals, cut into bogs, [is a familiar pheno- 

 menon which supports this view. 



Although the felted envelope of a bog is close enough at its 

 margins to ajQTord support to the fluid interior, it is often 

 broken by holes in the middle ; into these the soft, black fluid 

 of the interior oozes up, as everyone who has traversed a wet 

 bog is well aware. Through such openings rain-water may 

 make its way, and join the liquid accumulation below the 

 crust. 



All mountain bogs present very similar features ; and the 

 fact which appears most wonderful is not that they burst, but 

 that they do not do so more frequently. 



Evidently the crust, in its natural state, is, as a rule, equal 

 to the task which the contained water puts upon it, and it is 

 only when weakened by unusually deep cuttings that it gives 

 away. 



If this cause be considered sufiScient, it might be thought 

 unnecessary to discuss the question further, yet we think that 

 the eruption of the water from below, as Klinge suggests, 

 though not as he postulates sudden and violent, may some- 

 times, perhaps frequently, have played a chief part; that, 

 indeed, not a decrease in the support afibrded by the crust, 

 but an increase in the pressure of the contained fluid may have 

 been the last in a train of causes which brought about the 

 catastrophe. In the present instance the whole structure of 

 the country (fig. 4) would lead the geologist to suspect the 

 existence of springs : the southward dip of the beds forming 

 the rising land to the northward of the bog, would convey 

 subterranean water towards it from a large catchment basin ; 

 the fault underlying the bog would serve as a conduit, 

 through which this water would rise beneath it. The water 

 draining away from such a spring would give rise to the wet 

 line in the bog. The existence of such a spring would also 

 afford an explanation of the origin of the bog; about the 

 waters escaping from it, bog plants would naturally spring up, 

 and would thence spread outwards and upwards ; but since 

 their growth would commence near the spring, it is there that 



