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ON THE ERRATIC BLOCKS OF ENGLAND, TVALES, AND IRELAND. 115 



Seventeenth Report of the Committee, consisting of Professors J. 

 Prestwicii, W. Boyd Dawkins, T. McK. Hughes, and T. Gr. 

 BoNNEY, Dr. H. W. Crosskey, and Messrs. C. E. De Range, 

 W. Pengelly, J. Plant, and R. H. Tiddeman, appointp.d for 

 the purpose of recording the Position, Height above the Sea, 

 Lithologlcal Characters, Size, and Origin of the Erratic Blocks 

 of England, Wales, and Ireland, reporting other matters of in- 

 terest connected with the same, and taking measures for their 

 preservation. {Draiun up by Dr. Crosskey, Secretary.) 



It is still too soon to summarise the reports which this Committee has 

 presented, since new facta are constantly being brought to light. It 

 would be of great service if a committee like the ' Yorkshire Boulder 

 Committee ' were formed in every county ; were that done, the record 

 of English erratics could soon be made complete, to the great advantage 

 of the students of glacial geology. 



The Yorkshire Committee carefully examines the reports presented 

 to it by individual observers, and collects typical rocks to aid them in 

 the determination of the specimens sent. 



The valuable map of the distribution of erratics in the Midlands, 

 by Mr. Fred. W. Martin, F.G.S., which was exhibited in an unfinished 

 state at the Birmingham meeting of the Association, is approaching com- 

 pletion. It is strongly recommended that similar maps should be pre- 

 pared in other districts, erratics of different types being recorded in 

 various colours. Only by mapping will the remarkable facts connected 

 with their distribution be brought clearly out. 



The investigations of each year give fresh emphasis to the important 

 points which were noted in last year's report as being gradually brought 

 to light, viz. : 



(1) The grouping of erratics from distinct regions in distinct localities, 

 erratics from a special district being often found without the intermixture 

 of others. 



(2) The occasional intermixture of groups of erratics from different 

 localities, this intermixture being connected with the physical features of 

 the district, i.e., with the paths open for the ice to take, whether it de- 

 scended as a glacier from the higher hills, or floated in the shape of ice- 

 bergs over the submerged land. 



(3) The occurrence of erratics at such different levels as to necessitate 

 different explanations of the method by which they were distributed, the 

 high-level erratics demanding special consideration. 



(4) The distribution of trails and groups of low-level erratics in 

 accordance with the present arrangements of mountains, valleys, and 

 plains, so that their ' flow ' may be traced from their distant sources along 

 natural passages. 



It is not the duty of the Committee to submit any theories, but simply 

 to record the facts which have to be explained. What these facts are, 

 however, will become more apparent when a summary of these reports is 

 prepai-ed. 



TOKKSIIIRE. 



From the Yorkshire Boulder Committee the subjoined series of valuable 

 reports has been received ; Prof. L. C. Miall, F.L.S., having acted as its 

 chairman, and Mr. S. A. Adamson, F.G.S., as its secrotaxy. Mr. Samuel 



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