86 



What Evidence have we of Ice-Action 

 in Dorset ? 



By Dr. William T. Ord, F.G.S. 



Read before the Geological Section, January , 1910. 



T n considering a subject of such difficulty and importance as the 

 * Glacial Period and its effects as found in any given district, it is 

 necessary to use exactness of speech and in so doing to carefully 

 distinguish between fact and theory. This is the only scientific 

 method. To state that a certain deposit of such and such a nature 

 occurs at a certain spot is a matter of fact, to state that it has been 

 caused by an ice sheet 5,000ft. thick proceeding from Scandinavia is 

 theory. This may be true or it may not be true, but it cannot justly 

 be stated in the same terms as can a fact of observation. Whilst 

 the facts referred to in Dr. Colley March's paper are beyond dispute, 

 the theories advanced to account for them are matters of opinion, 

 which, although we should treat them with respect owing to the 

 high authorities adduced in their support, are nevertheless open for 

 our discussion this afternoon. 



Our consideration of the paper before us will naturally divide 

 itself into two sections, — Firstly the account of the glaciation of 

 England as briefly summed up on pp. 72 and 73, with various examples 

 on pp. 74 and 75 ; and secondly the account of supposed remains and 

 effects of ice action in Dorset and elsewhere as detailed in the latter 

 half of Dr. Colley March's paper. On pages 71 and 72 we are given 

 an admirable summary of the principal deposits usually attributed to 

 ice-action, with which we must all be fully familiar. 



As we all know the Glacial Period is a term used to describe the 

 last geological age immediately preceding that in which we live, 

 and which was characterised by an intense degree of cold, and the 

 formation of the superficial deposits I have just referred to. Now 

 whilst all geologists agree that at this time glaciation was proceeding 

 in the mountains of Scotland, the Lake district, North and South 

 Wales, and to a much greater extent than now in Northern Europe 

 generally, many take exception to the advanced views of those who 

 believe in a supposed vast glacier proceeding from Scandinavia, 

 filling up the North Sea and the Baltic, covering the whole of 

 Northern Europe, sweeping over Scotland and Ireland and whose 

 southern edge lay to the south of Ireland, and in England extended 

 to the valley of the Thames. And not content with this, in the 

 paper before us Dr. Colley March proposes to drag this terrific ice 

 sheet across the Bristol Channel, over the Mendips, and finally to 

 smother the county of Dorset beneath its icy mantle. Such is the 

 theory now presented to us for consideration. 



But on the other hand there are distinguished geologists who 

 dissent from this extreme view, some even who can hardly be said 



