W. B. Wright — Submerged Forests in Donegal Lakes. 119 



outlet is formed of thick peat, which connects with the outflowing 

 stream lower down, so that it is impossible to prove that the outlet 

 has not shifted. This lake contains some of the most beautiful 

 examples of submerged fir stools in the position of growth on both 

 its northern and southern shores. It is in many places cutting away 

 the peat at its margins, and exposing more stools both below and 

 above the present water-level. 



The remaining lakes which contain fir stools are Ultan, Aguse Mor, 

 and IS'avarnan. 



Lough TJltan lies on the crystalline schists about three miles north- 

 west of Pettigo and north of the Donegal Koad. There is a good 

 deal of deep bog round it, and the outlet is through peat. At the 

 south end of the lake there are some large submerged tree stumps in 

 the position of growth, and also several in the middle of the western 

 shore. 



Lough Aguse Mor is near the Black Gap, to the south of the Donegal 

 Koad, 5 miles W.^.W. of Pettigo. It is surrounded almost entirely 

 by bog, and has a sluggish outlet to the south through a level swamp. 

 Eine examples of submerged tree-roots in the position of growth 

 occur all round its northern and eastern shores, there being one 

 magnificent fir stool, 9 feet in diameter, on the eastern shore. 



Lough jSTavarnan is about a mile north-west of Drumgun Lough. 

 The outlet is to the south through a peat moss. It has evidently been 

 lowered by artificial cutting, for there is an abandoned shore-line round 

 the lake about two feet or so above the highest floods of the present day. 

 Submerged tree stumps can be seen at the north end of the lake. 



Now although it is exceedingly probable that the submergence of 

 the trees in all these lakes is due to the same cause, yet in any 

 argument based on the facts here presented we are bound to put four 

 of theui aside, because it is impossible to prove that they had not 

 lower outlets before the growth of the present peat-bogs. These four 

 are Afurnagh, TJltan, Aguse Mor, and Navarnan. Drumgun is 

 unconvincing for another reason— the submerged stumps in it are not 

 demonstrably in the position of growth. There remain to us Loughs 

 Bannus and Avehy. In these cases we are dealing with trees which 

 grew below the present level of the outlet, and it is necessary in the 

 next place to consider whether the outlet could not have been raised 

 by tilting since the growth of the forest. One can suppose a special 

 tilt for each lake, or a general tilting over a large area. Against the 

 first supposition it is difficult to produce any argument, and it is 

 certainly open to those who prefer such a hypothesis to adopt it as 

 an explanation of this peculiar phenomenon. There is, however, 

 a complete absence of any evidence of post-glacial folding or faulting 

 in Ireland. Indeed, there is distinct evidence against it in the 

 southern half of Ireland in the presence of a pre-glacial shore-line at 

 a uniform level all round the coast. This shore-line has, however, not 

 been traced into the north of Ireland, where the lakes under discussion 

 are situated. 



The hypothesis of a general warping or tilting of the country is 

 much more plausible, because in the north and east of Ireland a 

 deformation of this nature has been proved to have affected the 



