112 



SCIENCE-GOSSIP. 



THE BOG FLOW IN KERRY. 



"\ \ 7 HEN news reached Dublin on December 28th 

 last, to the effect that a bog had burst 

 rom its boundary at the head of the Ownacree 

 Valley, near Killarney, the Royal Dublin Society 

 appointed a Committee to investigate the fact. 

 This Committee consisted of Prof. W. J. Sollas, 

 Mr. R. Lloyd Praeger, Dr. A. F. Dixon and Mr. 

 A. D. Delap. They devoted the second, third and 

 fifth days of January, to the examination of the 

 " burst," and the Society has received their 

 report. 



It appears from this report that a dry summer 

 had been followed by a wet autumn, and on 

 December 27th a heavy downpour of rain set in, 

 with a south-easterly gale. It was about two a.m. 

 the following day that the bog gave way, and 

 flooded the valley below with a vast mass of peat 

 mud. No one seems to have seen it, nor in fact to 

 have been disturbed by any noise which may have 

 accompanied the event, not even the eight poor 

 people who were smothered in its course. So 

 extensive was this stream of peat and water, that 

 a portion of a bed which was in Donnelly's house 

 when swept away with its inmates was found 

 fourteen miles down the valley. 



The flow continued in an intermittent manner for 

 a day or two following the break, as fresh portions 

 of the bog gave way, the ruptures sounding like 

 the booming of distant guns. The bog occupied a 

 site 750 feet above sea-level, forming the watershed, 

 and draining into the Blackwater. It rested partly 

 on coal-measures and partly on carboniferous lime- 

 stone, separated from the coal-measures by a fault 

 running through the very middle part of the bog, 

 and adjacent to the site of the fracture. 



The cottagers and other residents say the bog 

 was a soft one; but they could at all times of the 

 year walk across it. The Committee examined the 

 flora of the remaining portion of the bog, but it 

 did not indicate more wet than is usual to like 

 sites, as Andromeda and cranberry (Vaccinium), 

 though searched for, could not be found. The 

 plants commonest in evidence were Calluna (ling), 

 Erica (heather), Narthecum (bog-asphodel), Scirfus 

 (clubrush) and Molinia (purple melic-grass). The 

 usual mat of Sphagnum was there, with tufts of 

 moss and reindeer-lichen. The stream of mud, as 

 it subsided, left behind large numbers of roots and 

 trunks of fir-trees, which, sticking up in all sorts 

 of fantastic shapes, added to the melancholy 

 desolation of the scene. 



The phenomena of a collateral nature attending 

 this bog-burst have been collected by the Com- 

 mittee, and are summed up as follows : (1) A dry 

 summer was followed by wet weather, and heavy 

 rain fell just before the outburst. (2) An earth- 

 quake which had its epicentre in Wales occurred 



in December, and is said to have been felt in 

 Miltown-Malbay and other places in Ireland. 

 This preceded the rupture of the bog by five 

 days. (3) The stream of the Carrundulkeen was 

 continued as a " wet line," or line of drainage, into 

 the bog. At the origin of this was a swamp. 

 (4) The neck of the bog was cut through by a 

 working face of peat, which thus crossed the line 

 of drainage. (5) The centre of the collapsed 

 portion of the bog stood, before the outburst, 

 seven feet higher than the sides. (6) The bog was 

 disrupted along the line of peat-cutting, and 

 liberated a deluge of water charged with peat. 

 The volume of the discharged material the 

 Committee estimated at about 6,000,000 cubic 

 yards. (7) As a consequence of this discharge 

 the crust of the bog subsided, so that after a lapse 

 of some days its centre had fallen thirty-five feet 

 below its original level, forming a depression with 

 a depth of twenty-eight feet. 



The cause of the outbust was believed to be from 

 the fact that the viscious fluid of the bog was 

 contained in a resisting wall, the pressure of the 

 fluid and the tension of the envelope being in 

 equilibrium. Owing to an increase of pressure, or 

 a decrease in the strength of the containing-wall, 

 this equilibrium was destroyed and ruptured in its 

 weakest part. The fluid peat, under a head of 

 pressure, rushed down the inclined plane provided 

 by the natural drainage of the country. 



Reviewing the explanations of bog-bursts, the 

 Committee rely chiefly on the theory of Klinge, 

 the latest investigator of such phenomena, who 

 propounds an entirely new theory, expressing 

 views differing from those usually held as to the 

 constitution of peat-bogs. He considers that 

 mountain bogs are of two different classes. Those 

 which have grown in uniform climate like that of 

 the western coast of Europe, characterized by a 

 continual increase in degree of decomposition from 

 their surface downwards ; and those which have 

 arisen under the influence of severe changes of 

 climate ; the latter consisting of alternate layers 

 more or less highly decomposed. The different 

 layers have different saturation limits of water, and 

 these limits once attained never alter. There is no 

 vertical movement of water through such a bog. 

 The Royal Dublin Society's Committee, above 

 referred to, consider that the Irish bogs belong to 

 the class in which decomposition of the vegetable 

 matter increases from the surface downwards. 

 The decomposed peat is heavier than the water, 

 and tends to accumulate at the bottom. The 

 upper crust, on which plants are found growing, is 

 formed of particles lighter than water, which float 

 to the top of the bog. Thus it is between the 

 crust and the heavier portion that most fluid 

 should occur. The Committee's report then 

 examines and discusses reports of the Com- 



