THE DIFFERENT LAYERS. 467 



richest green stratum (/)) there is a barely perceptible oozing 

 of water. All below dry, and the two last strata remarkably 

 dry. They could not be more so if within three feet of the 

 surface of a high knoll, and in summer. 

 1 foot (31 to 32 below tide) of same as the last in texture, but of 



pale blue colour. 



1 foot (32 to 33 below tide) mixture of the last, in small lumps 

 imbedded in the next, as if broken up by a violent current, and 

 deposited in rapid water. 



17 feet (33 to 49 below tide, the lowest digging) black earth 

 richest in green-sand (supposed to be 40 per cent.) mixed with a 

 few fragments (less than 2 per cent, on an average) of shells, 

 mostly small, and all very rotten. Kinds, mostly of turriteUa 

 (some of which are large), mytylus, corbula, and crassatella. 

 Many small and a few large shells of ostrea compressirostra near 

 the top of this stratum and again near the lowest part, where 

 the work was stopped by the water rising from below. 

 The whole, so far as dug, added to the before exposed bank, 

 amounted to 66 feet of the eocene deposit, of which 49 feet was 

 below the level of high tide. The last stratum, which was pene- 

 trated for 17 feet before the rise of spring water compelled the work 

 to be discontinued, was manifestly the same with that at Evergreen 

 which was even with high tide (and extending above and below), 

 and which was there 25 feet thick. It was a subject of much re- 

 gret, after so much labour, that the still lower stratum, full of shells, 

 could not be reached, and which probably might have been done in 

 8 feet more of digging. However, enough was done to show that 

 the quantity is inexhaustible of the layers richest in green-sand 

 (whatever may be that degree of richness), independent of the 

 other layers. 



Besides the main object of this laborious examination by digging 

 as low as possible, to learn more of the quality and quantity of the 

 earth for manure, and as a matter of curiosity, there was another 

 inducement. The whole bottom of the river across to Berkley 

 (below the thin covering of loose and soft mud), according to its 

 variation of depth, must be formed of one or another of the same 

 layers shown in this digging of 49 feet below the water level j and, 

 of course, Harrison's Bar, which lies between the Coggins and 

 Berkley shores, must be so formed. No earth more strongly re- 

 sists the washing action of water than the gypseous earth, even 

 when the least mixed with clay. This peculiar quality must bo 

 the cause of the existence of this bar, which presents so serious an 

 obstacle to the navigation of the river ; and it may be thence in- 

 ferred what would be the degree of difficulty of its removal, and 

 also that the removal, if effected, would be permanent. 

 Various and contradictory as had been many of the results of 



