40 THE BlilLPTXC OF AN ISLAND. 



further that the sea, at one time durinij the long period of the piling up of the 

 clay rocks, not only received and arranged all this material, but also furnished 

 its own quota in the shape of a few limestone beds, which in some parts, as in 

 the limestones at St. John's estate, are so nearly pure as to contain over 90 per 

 cent, of carbonate of lime; in other parts, as at Waiter's Point, mostly impure, 

 but containing numerous fossils of considerable interest. 



The presence here and there of limestone beds in the blue-beach forma- 

 tion, taken together with the power of carbonic acid to dissolve carbonate of 

 lime, suggests to us that after all there mav have been other, even though less 

 abundant, deposits of lime elsewhere throughout the formation, deposits which 

 have disappeared under the dissolving process. In that case we should be in 

 error if we inferred from the absence of such beds an absence of sea-life during 

 the period or its powerlessness to leave anv record. And this view of the 

 matter is strengthened by the fact that some of the older rocks do contain a 

 fair amount of lime in their composition. In the northwestern hills the 

 presence of lime in the rock is shown in a most interesting way. On the road 

 up the hill from " Little La Grange " to " Punch " an old watercourse is cut 

 through, in which some exceedingly curious deposits of limestone may be seen. 

 The limestone is in masses having rounded tops, and when carefully examined 

 is found to be light and porous, to be made up, in fact, of small cells, some- 

 what irregularly arranged in thin layers, one over the other. The rock also 

 contains impressions of stems and leaves. The origin of this singular rock, 

 which is called ''Travcrtiney maybe seen in the neighbouring stream that 

 passes down the beautiful vallev known as Crequi's. There some of the larger 

 blue-beach rocks in the bed of this stream may be seen to have acquired a 

 similar rounded form, the covering being a substance composed of like 

 material, and if examined while the water runs over them, thev will be found 

 to be covered with a slimv vegetable growth, a growth which doubtlessly 

 absorbs the lime brought out of the rocks bv fresh water, and on the subsidence 

 of the water dies, leaving a limestone crust. Such crusts deposited one over 

 the other, through a long period, make the blocks such as we see in the above- 

 mentioned old stream-bed. No similar growth of Travertine has been found 

 by the present writer in the other streams of the island ; but in the watercourse 

 which passes out into the plain near Grove Place, lie has found among the 

 pebbles a water-worn fragment of this curious rock, proving its existence 

 higher up in the stream's course. While, therefore, the great preponderance 

 of the clay class of rocks in the blue-beach formation is obvious, we have to 

 modifv our conclusions so far as to admit that the lime deposits may have been 

 originallv more numerous than now appears. 



Although we have thus come to a conception of the origin of our older 

 rocks, which is probablv near the truth, there remain many interesting points 

 in regard to thein yet to be studied. 



The crvstallization of many of the rocks, which obliterates the stratification, 

 and the weathering whicii so often reveals it again, havi' alreadv been men- 



