Impressions of Bain-drops in Strata. 73 



the deepest extremity of the excavation where they often 

 overhang. 



The carboniferous rain-prints of Sydney, Cape Breton, 

 observed by Mr Richard Brown, are some of the most deli- 

 cately sculptured on the laminae of shale. In some specimens 

 they are quite separate from each other, most of them oval 

 and with distinct rims. Mr Brown remarks that they only 

 extended over a certain narrow zone, disappearing when the 

 stratum containing them was traced further in each direction ; 

 so that they appear to have constituted a narrow belt, as 

 might be expected if they were formed on a sea-beach. For 

 when rain falls on recent mud bordering the Bay of Fundy, 

 impressions are only made on one portion of the exposed sur- 

 face, the upper part of the bank (left dry for ten days or more 

 after the highest spring tides), being too hard to receive any 

 imprints, and the lower part near the water's edge being too 

 soft. In some shales from Cape Breton, perfect casts are 

 seen projecting from an under surface where the drops are 

 few in number, while in another stratum distinct casts of 

 a heavy shower are preserved in a fine-grained sandstone 

 which presents a warty and blistered appearance. The casts 

 also of small cracks, which must have traversed the subjacent 

 clay, stand out in relief. Together with these memorials of 

 rain are seen numerous winding cylindrical cavities, open at 

 the top and precisely resembling these now formed by anne- 

 lids on the recent mud of the Bay of Fundy. These strata 

 occur in the same series of beds, in which so many examples 

 of buried forests occur, with the trunks of trees standing 

 erect, and having their roots attached to them. There are 

 also numerous rippled sandstones at different levels in the 

 same formation. 



On re-examining the slab which he brought in 1846 from 

 the coal-strata of Greensburg, Pennsylvania, on which Dr 

 King first found impressions of a carboniferous reptile, Sir 

 C. Lyell finds not only shrinkage-cracks but a multitude of 

 small tubercles covering the surface resembling the casts of 

 rain-prints^ and which he can scarcely doubt are referable to 

 pluvial action. 



In conclusion,. the Lecturer enlarged on the important in- 



