XCIV PEOCEEDES'GS OP THE GEOLOGICAL SOCIETY. 



holes in the fields, and sometimes in the roads, receiving leaves, fruit, 

 branches, shells, and other substances with every great spring-freshet 

 — all these once had their analogues in time past. 



The author then submits that, by thus reconstructing the older 

 surfaces, we obtain a reasonable explanation of the sporadic masses 

 of lignite, two of which are now known to exist in, or rather near, the 

 iron-ore. It is only necessary to suppose a sink-hole so formed and 

 so stopped up below as first to receive and then to retain an accumu- 

 lation of forest-trash, and we have the thing ready made to our hand. 

 The author then proceeds to describe in detail the ore-banks of Mont 

 Alto, and the relationship of the lignite to the ore. The ore is in fact 

 nothing but the residue of the Silurian slates and sandy limestone 

 beds after decomposition and dissolution, after the lime has been 

 washed out and their carbonated and sulphuretted iron has been hy- 

 drated and peroxidized, the muddy slates forming the present de- 

 posits of small ore with white and red clay, while the sandy Hmestone 

 formed the present harder siliceous rock ore-belts. He concludes with 

 some statistical details respecting the enormous masses of haematite 

 contained in this remarkable formation. 



As showing the intensity of geological changes now in operation,M. 

 Jules Marcou gives an account, in the ' Bulletin de la Soc. Geol. de 

 France,' of the result of his observations on the Palls of Niagara after an 

 absence of fifteen years. Some of these changes are very remarkable. 

 Looking at the falls from the Victoria point on the Canada shore, he 

 says that he could not observe any sensible change in the fall on the left 

 of the spectator, which is the American fall ; but he was much struck 

 with the changes which had taken place in the great fall to the right, 

 known as the Canadian or horseshoe fall. The horseshoe form, 

 which was tolerably regular in 1850, has been greatly modified, being 

 considerably worn away and deepened in the centre. The table rock 

 has almost entirely disappeared ; also the tower known by the 

 name of Terapine is nearer to the edge of the fall, on which side the 

 mass of water appears to have increased, while it has diminished in 

 volume near the table rock ; there also appears to be a slight dimi- 

 nution in the volume of water passing by the American fall, be- 

 tween the American side and Goat Island. 



He thus tabulates the results of his observations : — 



1. The American fall retreats very slowly, and, compared with 

 the Canadian fall, might be said to be almost stationary. 



2. The volume of water in the American fall is constantly decreas- 

 ing, and will continue to decrease in proportion as the Canadian fall 

 retreats ; and when the latter shall have reached the islands of the 

 Three Sisters, viz., in eight or ten centuries, no more water will 

 pass by the American fall. Goat Island will be joined to the 

 mainland. 



3. The Canadian fall is rapidly retreating, although it is impossible 

 to give any rule of its annual retrograde progression, which varies 

 from year to year. 



4. The mass of water in the Canadian fall increases as it diminishes 

 in the American faU, besides which it is leaving the Canada shore, 



