TRANSACTIONS OF SECTION C. 577 



formidable diliiciillies that they have inspired appeals to -geological catastrophes. 

 The special problem of these deposits is rhe occurrence of low-level glacial beds in 

 or near the tropics. In Australia there are glacial deposits on at least three 

 horizons — Cambrian, Carboniferous, and Pleistocene. 



The Cambrian beds occur east of Adelaide, aud range 400 miles north and 

 south. They are interbedded with marine beds with a rich Cambrian fauna. 



The Pleistocene glaciers ou the mainland of Australia, so far as has yet been 

 fully established, were limited to a few comparatively small glaciers around the 

 summit of Mount Kosciusko, the highest mountain of Austi'alia. 



The Carboniferous glaciation of Australia is the most important. The fact of 

 the glaciation is indisputable, and present interest is concerned with the nature 

 and extent of the ice agent. In Victoria this can now be accepted as land ice, 

 working on au irregular land-surface, on both tlanks of a mountain range which then 

 extended E. aud W. across the State. The glacial beds of New South Wales, 

 West Australia, and India include some that were laid down beneath sea-level. 

 Glacial deposits of the same age occur in South Africa, India, and South America, 

 and possibly also on the eastern flanks of the Urals. 



These beds have been represented as part of a ouce continuous sheet of glacial 

 deposits ; but the evidence does not support this view. The glaciation in each 

 case developed from a series of local centres ; and the glaciations at all of them 

 were not necessarily synchronous. The glacial evidence in Africa and Australia 

 disappears to the N., ending about the southern tropic; and in the northern 

 hemisphere it begins again at the lat. of 17° 20' N. and increases in strength north- 

 wards to Cashmere. 



Three chief groups of theories have been advanced to explain this problem : 

 (1) The shifting of the South Pole into Africa (Oldham), or into the Indian Ocean 

 (Penck) ; but the absence of evidence of any corresponding movement of the North 

 Pole is opposed to this idea. (2) A universal refrigeration of the world, due to a 

 change in the composition of the atmosphere (Arrhenius) ; but this theory appears 

 to be a chemical impossibility owing to the action of the sea, and is opposed to the 

 facts that require explanation. (3) The geographical theory — local concentrations 

 of snowfall in consequence of a difterent distribution of land and water. It was 

 claimed in the paper that the agencies appealed to by this theory are adequate to 

 explain the facts : the glaciations were local and sporadic ; they were not all syn- 

 chronous ; they were developed on mountainous regions on the borders of the con- 

 tinent of Gondwanalaud, in the neighbourhood of warm seas. They occurred 

 where there was an ample supply of moisture from the sea, high mountains to 

 precipitate it as snow, and a distribution of land and water that would have pro- 

 duced a suitable wind system and low summer temperatures. The proved facts of 

 the Gondwanalaud glaciation can be explained by the action of existing meteoro- 

 logical forces acting on their present scale. 



5. On the Artesian Boring for the Supply of the City of Lincoln from the 

 New Red Sandstone. By Professor Edward Hull, LL.D., F.B.S. 



Down to the present time since the year 184" — when the waterworks were 

 commenced by a public company — Lincoln has depended for its supply of water 

 upon surface streams, impounded into reservoirs and subjected to a filtering process, 

 the quantity dealt with amounting to about 331 millions of gallons a year, with a 

 rainfall of about 25 inches.' Needless to say, a supply from such sources was found 

 to be unsatLsfactory on the grounds both of quality and quantity. In 1885 Dr. 

 Harrison was requested to report on the former of these subjects, and he produced 

 elaborate analyses, the general result being that, as some of the sources were liable 

 to pollution, the water was unfit for domestic purposes.- 



Owing to the rapid growth of the city the conditions became more unfavour- 

 able, and it was determined by the Corporation to ascertain whether some better 



* Average of fourteen years from 1870 to 1884 inclusive. 

 ' Bejjort respecting Water Supply (1885). 



1906. PP 



