KiNAHAN — On the Leimter and Tipperary Coal Seams. 369 



thickens, to thin again when the floor rises. These phenomena, in 

 connexion with the formation of the channel, appear important, as 

 will be mentioned hereafter. 



It appears necessary to point out here, that in my previous 

 writings and in those of later observers, a very important con- 

 sideration has been omitted, or rather mis-stated, as the promis- 

 cuous calling of the seam One-foot coal and Jarroic coal leads to an 

 erroneous impression ; because although they are connected, the 

 latter being an adjunct of the former, the One-foot coal is perfectly 

 distinct from the Jarroic Channel ; for although both may have 

 been accumulating at one and the same time, their modes of for- 

 mation were very different ; one being almost entirely a drift 

 accumulation, and the other a growth in situ. I have not met 

 with any description of a coal similar to that in the Jarroiv Channel, 

 but the probable explanation of its peculiarities would appear to 

 be suggested by what can be observed as going on at the present 

 day in various places in the Irish bogs. Numerous cases could be 

 mentioned, both in the Irish lowland or Red Bogs, and in the 

 mountainous districts. I will, however, draw attention to but one 

 locality, which is specially illustrative — that is to say, the level 

 bog-land in the neighbourhood of Muckanaghederdanhalia, Conne- 

 mara, West Gralway. In this locality there is a great expanse of 

 low bog-land intersected by more or less regular wash-outs ; some 

 of the latter being fiords, while the majority of them are now 

 marshes or sloughs ; the latter having been, or being now filled in, 

 by materials carried by wind, rain, and runlets from the adjoining 

 flats, aided by the growth and decay of vegetation ; while on the 

 adjoining flats peat is accumulating in the ordinary way — that is, 

 by the growth and decay of vegetation in situ. Some such more 

 or less similar operations must have been going on in Carboniferous 

 times, to account for the formation of the Jarrow Channel. The 

 One-foot coal seems to be of a somewhat similar origin to the flat 

 bog, being due to the growth and decay of vegetation in situ, 

 while through it there ran a washout, now the Jarroic Channel; it 

 having been subsequently filled in by argillaceous and vegetable 

 matter carried into it by wind, rain, and runlets, the accumulation 

 being aided by the growth and decay of aquatic plants. Besides 

 the plants in the nearly stagnant or sluggish waters, there lived 

 fish and batrachians ; and these, in course of time, as the filling-in 



