2 42 



KNOWLEDGE. 



[NOVKMBER, 1902. 



arcouiit for llio former wide ilisiril)uf.ion of pine ;inil oilier 

 woods. .Similarly, the passing' away of llie forests, and 

 their n^idacement l>y Siiliinjiiiim a,i>d the hog-tlora, minht 

 well be conuected with those geologieal changes which, 

 giving our islands their present contour by depression of 

 tiie land, brought in a milder and wetter insular climate. 

 In our great peat-bogs, these forest-growths are confined 

 to the lower layers. The main mass of the jjeat has 

 been formed by Sphagnum and its associated jdants after 

 the forests passed away, and under the influence of a wet 

 Cold-Temperate climate. The old forests have been deeply 

 buried, and the bog-flora has reigned supreme in the 

 British Isles, especially in the north and west, and 

 since the beginning of history has furnished the most 

 remarkable feature of the floral characteristics of our 

 country. 



So much for the origin and growth of bogs. Like 

 everything else on this earth, their life is limited. They 



strumentjil in Imilding up the b<»g8, still grows bixuriantly, 

 and there is no indication in many cases that the bogs are 

 not st ill growing as fast as they ever grew. Hut on some bog.s 

 the lu.xuriant cushiony growth of Sphagnum, mixed with 

 Eriaphorum, Nin-lhi'cinm, Khijnchns^porii , gives place to a 

 thin scrubby vegetation from which Sphagnum is absent, 

 and among which the bare sodden peat continually forms 

 black patches. Such a bog, though on level ground not 

 yet actually wasting away, is dead so far as growth is 

 concerned. Elsewhere a luxuriant crop of Ling rejdaces 

 the many-coloured Sphagnum, and tells of a diminution of 

 water supply. Such a bog is near its end, for Ling cannot 

 form peat. But it is on the hills, among the bliwk bogs, 

 that signs of decay are most clearly evident, ju.st as Prof. 

 Geikie has pointed out as regards the Scottish hills. Thus, 

 Kippure (2473 feet), the highest point of the Dublin hills, 

 shows, even at a distance of some miles, a slightly serrated 

 crest. This is found on ascending to be due to the fact 



Scotch Fir, witli Peat above and below it: Co. Antrim. 



[R. Welch, fhoio. 



do not go on growing for ever, and it would seem that the 

 Age of Bogs, as we may call it, through which these 

 countries have been passing for the last few thousand 

 years, is now on the decline. Prof. James Geikie is of 

 opinion that bog-growth is waning in Sjotland. Regarding 

 this he speaks with no uncertain voice : — " A glance at 

 the present aspect of our peat-mosses will convince any 

 geologist that this formation has not only ceased to spread, 

 but is in most cases rapidly diminishing. The moisture 

 which in former times afforded it nourishment and support, 

 has now become its chief enemy. Every shower of rain, 

 every frost, gives fresh imjjetus to the decay ; and leaving 

 altogether out of account the operations of agriculture, 

 we can yet have no doubt that natural causes alone would, 

 in time, suffice to strip the last vestige of black peat from 

 hill and valley. . . . The peat-mosses of Scotland are 

 thus only a wreck of what they have once been."* 



On the Irish bogs the signs of decay are not so general 

 nor apparent, but many interesting individual case.s may 

 he studied. On the great red bogs of the Central Plain, 

 l)og-moss or Sphagnum, the jilant which has been chielly in- 



* ioc. piV., pp. 381,382, 



that the great cap of peat, 12 feet or more in thickness, 

 has been cut into by wind and rain, and eaten away till 

 stretches of bare disintegrated granite alternate with great 

 bastions of peat, capped with a growth of Ling. Peat so 

 exposed will disappear rapidly. Eaiu, frost, and drought 

 alike play havoc vsdtli it, and wind and streamlets carry it 

 down the hill-side. In many other places, where deep 

 deposits of peat prove a former luxuriant bog-flora, the 

 vegetation now consists of dry wiry grasses, such' as 

 Nai-(his stricta, with stunted Ling and Wliortle-berry. 

 Such a plant-group will never form peat ; the plants 

 which made the deposit on which they grow are dead and 

 gone. To compensate for the decay of the peat-flora, we 

 do not find that in any portion of the country fresh bogs 

 are forming ; and we are driven to conclude that the 

 formation of peat is on th(> decliue. While man's ojiera- 

 tions are responsible for the destruction of much peat, by 

 turf-cutting and by drainage and cultivation, this cause is 

 wholly insufficient to account for the facts, as the best 

 instances of bog decay are seen in situations whiih the 

 operations of man have never extended to, or even indirectly 

 affected. Some change of conditions must be looked for 

 which has affected the whole country, and Prof. Geikie 



