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to the Caithness stone, some specimens of which might be seen 

 near the Post Office. That was mud consolidated by the lapse of 

 ages, and in which had lived and died myi'iads of creatures, the oil 

 from whose bodies gave it that greasy appeai-ance so observable. 

 Coming to a more recent formation, it would be seen, when passing 

 thi'ough Clayton Tunnel towards London, they came upon a large 

 expanse of comparatively flat country. This was an estuary of the sea, 

 in which a mighty river once poured its flood and deposited its mud. 

 This extended over a large district which existed where the English 

 Channel now was, and could be distinctly seen on the opposite coast. 

 After passing through the wealden district they came to the north 

 down, composed, as were the south downs, of chalk. Unquestion- 

 ably, the north and south downs wei'e connected, and covered the 

 space where the wealden clay now existed. This chalk extended to 

 London and beyond ; and as all chalk was formed at the bottom of 

 the sea, it followed that where London now stood the sea once 

 ebbed and flowed. The hills sui-rounding Brighton were of chalk, 

 and the London and Lewes roads were the valley through which 

 rivers ran. Within their own time they might see some of these 

 changes. Thirty years ago he visited Offham chalkpits to collect 

 specimens. Barges for the conveyance of the burnt chalk or 

 lime were brought to the foot of the hill. Last summer he was 

 there ; and the barges could not approach within half a mile of the 

 same place ; that which was covered by water had become dry land. 

 Above the chalk the London clay was found. That formation 

 cropped up in their own neighbourhood, and in it had been found 

 many plants now grown in tropical regions. He had omitted any 

 reference to the intermediate strata. Did time allow, he would call 

 their attention to the carboniferous, in which coal was found — the 

 vegetable remains of a past time. Buckland said that, in the coal 

 mines of Bohemia, the most elaborate imitations of living foliage 

 upon the painted ceilings of Italian palaces, bore no comparison 

 with the beauteous profusion of extinct vegetable forms with which 

 the galleries of these instructive coal mines were overhung. The 

 roof was covered as with a canopy of gorgeous tapestry, enriched 

 with festoons of most graceful foliage, flung in wild irregular pro- 

 profusion over every portion of its surface. The effect was 

 heightened by the contrast of the coal black colour of these 

 vegetables with the light groundwork of the rock to which they 

 were attached. The spectator felt himself transported, as if by 



