1894- SOME NEW BOOKS. 379 



When Professor Lewis came first to England the generally- 

 accepted theory was that this country had twice been covered by a 

 vast ice-sheet, and in the interval between these had been submerged 

 to the depth of over 1,400 feet at the very least. One school occupied 

 the extreme position of denying the influence of land-ice in any form, 

 and explained the whole thing as due to icebergs drifting southward 

 during a period of submergence ; this view, however, was very 

 restricted in its distribution, and there was an overwhelming majority 

 for the orthodox side. A few men had advocated other views, notably 

 J, G. Goodchild and T. Belt ; they believed in one ice-age, denied 

 any submergence, except locally to a very small amount, main- 

 tained the power of ice-sheets to raise boulders and frozen masses of 

 shell-beds from lower to higher levels, and realised the effects of the 

 differential movements that must occur in ice-sheets flowing over 

 uneven surfaces. But these teachers had exerted barely any per- 

 ceptible influence ; their views was based on the complexity of the 

 conditions of glaciation, whereas geologists preferred to regard these 

 as very simple. Goodchild's remarkable paper on the " Glacial 

 Geology of Edenside " appeared in 1875, but it was before its time 

 and was practically ignored. 



In opposition to the orthodox theory. Professor Lewis advocated 

 the unity of the ice-age, at least until his discovery at Frankley Hill, 

 and strenuously opposed the great submergence. He admitted that 

 the north of England and Scotland had subsided for about 150 feet, 

 and attributed all the deposits formed by water above this level to 

 the action of either lakes or subglacial streams. The shells, he thought, 

 worked their way up through the ice in frozen masses, just as boulders 

 do through the Swiss glaciers. These views are expressed in the 

 volume in five short papers. These are entitled, " Comparative 

 Studies upon the Glaciation of North America, Great Britain, and 

 Ireland " ; " The Terminal Moraines of the Great Glaciers of 

 England"; " On some Important Extra-Morainic Lakes in Central 

 England, North America, and elsewhere, during the period of Maxi- 

 mum Glaciation, and on the Origin of Extra-Morainic Boulder Clay " ; 

 "The Supposed Three-fold Division of the Drift"; and "The 

 Direction of Glaciation as ascertained by the form of the Striae." 

 These essays, however, he left only in abstract. Most of the volume 

 consists of his field notes, and contains descriptions of sections and 

 country in many parts of Ireland, England, and Wales. The 

 districts that he knew best, and where he has added most to our 

 knowledge, are the south-west of Ireland and northern Donegal, 

 Shropshire, and South Lancashire ; his description of the sections 

 in these localities must prove of great service to English 

 geologists. 



One of the principal difficulties in using this part of the work is 

 the varying meaning attached to the same term, and the frequent 

 changes of position which were necessitated by increasing knowledge, 

 and no one can read the volume without feeling what we have lost by 

 the fact that Professor Lewis did not live to state his case finally and 

 fully in the light of his latest conclusions. Many of the views 

 expressed we know he modified the year before his death, and he had 

 come to England to re-investigate the changes that were inevitable 

 after his abandonment of his view of there being but a single 

 glaciation. 



But in spite of his early death he had lived to do much. He 

 had unquestionably cleared the ground of many stumbling blocks. 



