Mineralogy and Geology of apart of Nova Scotia. 323 



formation of the cavities, as the incrustation always received 

 its impressions from the irregularities of the tube, and never 

 left any, although it received an indentation from the slight- 

 est prominence in the rock. The only way in which we can 

 account for these cavities, on the supposition that the rocks 

 were of aqueous origin, would be, to suppose the upright 

 tubes to have been produced by the ascent of some elastic 

 gas ; but as the cavities are soon arrested by a dense super- 

 incumbent rock, and have no outlet, and at the same time 

 diminish in size as they ascend, there is reason to suppose 

 the cavities to have been produced by some condensible elas- 

 tic fluid, as steam. Their position shews the force which 

 produced them to have acted in a direction up and down, 

 and their irregularities perhaps indicate the rising and fall- 

 ing of the fluid mass. 



We shall take occasion hereafter to shew the relations of 

 shale, red sandstone and trap, in the production of trap-tuff 

 and amygdaloid, which will lead us to infer, that the vicinity 

 of the trap is necessary to the formation of amygdaloid, and 

 that the production of that rock was attended by heat. 



Before leaving this cove, we would mention that foliated 

 heulandite occurs in veins two or three inches wide in the 

 amygdaloid, and that mesotype is found abundantly in the 

 soil formed by the disintegration of this rock. 



From St. Croix Cove, pursuing the coast easterly, the 

 amygdaloid, crowned with columnar greenstone, continues 

 and forms an abrupt precipice for five miles, where it is 

 again interrupted by Martial's Cove. — The rocks at this 

 place, and the ruins which the neighboring shore presents 

 cannot fail to reward the labor of those who may visit this 

 locality, as scarcely a week passes, without the downfall 

 of some impending steep, which scatters its treasures along 

 the shore, before shaded by its brink. Here the heu- 

 landite is not confined to spheroidal masses, as a mere 

 constituent of amygdaloid, but exists in veins sometimes 

 six inches wide, extending vertically from the base of the 

 precipice to its extreme verge. Some of them which have 

 fallen in connexion with the immense massess of greenstone, 

 exhibit broad laminae of a pearly white appearance. It is 

 usually colorless and transparent, but in one or two instan- 

 ces, specimens were found of a red color resembling those 

 brought from Scotland and Germany. But in speaking of 

 the interesting productions of this place, we should not pass 



