W. B. WrigJtt — Submerged Forests in Donegal Lakes. 115 



between the slates and the arenaceous Pickwell Down Beds, though 

 the relations of the rocks are somewhat obscured by the surface- 

 slipping that has taken place. 



There is reason to believe that not only the Morte Slates but also 

 a considerable portion of the Ilfracombe Beds belong to the Upper and 

 not the Middle Devonian, with which they are usuallj^ classed. For 

 String ocephalus Biirtini, Defr., whicli marks the highest horizon in 

 the Middle Devonian, appears to occur near the base of the Ilfracombe 

 Series in the Combe Martin Beds, and Calceola sandalina, Linne, 

 which is the characteristic fossil of the Lower Middle Devonian, is 

 wholly wanting, while a variety of Spirifer Verneuili is found in 

 a quarrj' above Killage Point, which should be comparatively low 

 down in the Ilfracombe Beds, and RhynchoneUa cuboides, Sow., which, 

 like Spirifer Verneuili, is not found below the passage beds on the 

 Continent, is also met with. Through the kindness of Professor 

 McKenrij^ Hughes, Dr. Evans had had an opportunity of seeing 

 a well-preserved specimen of Spirifer Verneuili from Caple Pit, near 

 Ilfracombe, which is believed to represent the same horizon. 



The ascription of the iVlorte Slates to the Upper Devonian is not 

 new. As early as 1889 they were placed by Mr. Ussher partly in the 

 Middle and partly in the IFpper Devonian (Eep. Brit. Assoc, 1889, 

 p. 801), and in the same year Professor Kayser compared them with 

 the Frasnian (Neu. Jahrb. fur Min., etc., vol. i, p. 181, 1889). 



The conclusions to which the authors have come with regard to the 

 age of the slates of Barricane Beach do not necessarily apply to the rocks 

 which have been included under the same name in Western Somerset. 

 So far as their work has proceeded in that area it shows that the 

 beds vary considerably in character, and are probably, as Dr. Hicks 

 suggested (Q.J.Gr.S., vol. liii, p. 438, 1897), of very different ages; 

 though whether they can be assigned to the horizons to which they 

 were referred by him and Mr. Whidborne is a point on which the 

 authors must for the present refrain from expressing an opinion. 



It may be added that Mr. Ussher, who has done a considerable 

 amount of work in West Somerset which has never been published, 

 has volunteered to co-operate with them in that area. 



VI. On the OcCtTRRENCE OF SUBMERGED PoRESTS IN CERTAIN InLAND 



Lakes in Donegal, 



By AV. B. Weight, B.A., F.G.S., Geological Survey of Ireland. 



[Published by permission of the Director.] 



FOE, many years past the Swedish geologists have been directing 

 the attention of the scientific world to the curious phenomenon 

 of the occurrence of submerged forests in certain of their inland lakes. ^ 

 In our own countrj^ such evidences of change of level are a familiar 

 sight along our sea-coasts, and, if we bear in mind the extreme 



^ Eutger Sernander, " Om forekomsten af subfossila stubbar p§. Svenska 

 insjoars botten " : Bot. Not., 1890. German translation in Bot. Centralbl., 

 Cassel, Bd. xlv, 1891. 



Arel Gavelin, " Studier ofver de postglaciala niva- och klimatforandringarna 



