Mineralogy and Geology of apart of Nova Scotia. 137 



and lying confusedly in various directions ; the sandstone 

 has changed to a dark red color, is more compact, and has 

 become intimately blended with the shale, so that the eye 

 with difficulty distinguishes the substance peculiar to each. 

 The sharp angular fragments of the trap are next observed, 

 and the whole becomes a distinct breccia, growing more 

 compact as it dips beneath the superincumbent rock. That 

 portion of the breccia in contact with the trap exhibited the 

 small cavities of vesicular amygdaloid, as it passed into its 

 dominion, and led us to believe that the shale and sandstone 

 combined with the trap, and produced amygdaloid by their 

 union. The numerous instances in which this occurred, as 

 it did in fact at every junction of these rocks in Nova Scotia, 

 and the absence of trap tuff and amygdaloid in places where 

 this did not happen, or where, although the sandstone, &c. 

 ■were not visible, it could fairly be inferred to exist beneath, 

 led us irresistibly to this conclusion. That this process was 

 attended by heat is inferred from numerous circumstances, a 

 few of which can be mentioned here, and others in treating 

 of the two great divisions of the country which remain to be 

 described. The occurrence of native copper in the trap tuff 

 and amygdaloid, may be regarded as evidence in favor of 

 this; the conversion ofclaystone into fine red jasper, as it 

 entered the superincumbent trap ; the cyhndrical cavities in 

 the amygdaloid at St. Croix Cove ; and even the existence of 

 vacant spheroidal cavities may be considered as internal ev- 

 idence in favor of this theory. The change of color in the 

 sandstone from grey to red, and the compactness of the 

 strata as it approached the trap ; the absence of organic re- 

 mains, and the charred state of the vegetable remains in the 

 neighboring strata, give sufficient evidence, that, during 

 the formation of the secondary trap in Nova Scotia, there 

 was considerable heat. The sharp fragments of the breccia, 

 and the breaking up of the strata, also shew, that the produc- 

 tion of this rock, or rather its non-conformable position on 

 the sandstone strata was effected suddenly. Whether it was 

 ejected from the inaccessible depths of the Basin of Mines, 

 or was thrown directly up through the strata of sandstone, 

 we cannot determine ; but the occurrence of the trap only 

 on the borders of the basin which it almost surrounds, would 

 lead us to the belief that this cavity was the crater, if it may 

 be so called, from which, in former times, the trap rocks issu- 

 ed. The same remarks will apply to the whole North Moun« 

 Vol. XV.— No. L 18 



