9 10 Proceedings of the Royal Irish Academy. 



The above statement summarizes the results of observations made in 

 most counties in Ireland, and, briefly put, brings out the fact that Pine and 

 Birch occupy or lie beneath the older parts of the bogs, while Oak, Pine, 

 Yew, and various broad-leaved species occur near the margins. Exceptions 

 to this rule may be found in some of the small marsh bogs in mountain 

 districts, which may only contain Pine and Birch, while in a few shallow 

 lowland bogs Oak may be found predominating throughout. Two points are 

 quite clear, one being that the Pine was an earlier occupant of many sites 

 than the Oak, and the other that the Oak and Pine formed a mixed forest 

 at a later period, while it is fairly evident that the more pronounced 

 Sphagnum stage of peat-formation is invariably treeless so far as the bogs 

 alone are concerned. 



Observations made in various parts of the Continent of Europe agree 

 generally with the above view regarding the succession of forest associations 

 found in bogs. Papers contributed to the Eleventh International Geological 

 Congress in Stockholm in 1911 1 dealt with bog- formations in Norway, 

 Sweden, Germany, Holland, Denmark, and other countries, and the writers 

 are fairly unanimous on this point, although considerable differences of opinion 

 exist as to the causes responsible for the tree and treeless stages respectively 

 of the bog-formation. Van Baren (Holland) gives Pine and Birch as the 

 oldest association, after which came Lime, Hazel, and Alder, and finally 

 the Oak. Stoller (Germany) gives Birch, Willow, and Arctic Birch ; then 

 Pine and Birch; later Alder, Hazel, and Oak, with Birch and Pine; and 

 finally Alder and Beech ; and assumes that the Oak-Hazel-Alder association is 

 of the same age as the submerged peat of the North Sea coast. Andersen 

 (Sweden) supposes that Birch formed the first forest belt along the west 

 coast, and Pine and Birch further east. After Pine forest had prevailed 

 for a long period, a rise of temperature brought in a broad-leaved forest 

 which pushed out the Pine. Wahnehaffe (Germany) gives Birch and Pine : 

 then Oak, Alder, Fir, Birch, and Lime ; the latter association being contem- 

 poraneous with the submerged forests. 



On the other hand, Kinahan 2 and many other recorders of timber in 

 Irish and British bogs mention the Oak as occupying the lowest position, 

 with Pine coming in later ; but it is highly probable that these statements 

 are clue to the fact that the Oak invariably lies at the edges and shallower 

 parts of the bog, where turf-cutters would quickly come upon it on the 

 natural soil. "When the Pine layer was reached, the fact that it lay above 



" Die Yei-anderungen des Klimas seit dem maximum der letzten Eiszeit," 

 Geology of Ireland, 



