GENERAL DISTRIBUTION. 



87 



active volcanoes poured out their lavas on the grandest scale in the 

 ■waters and on the shores of the bay while its sandstones were being 

 formed. "While the New Red Sandstone of Nova Scotia is limited to 

 the Bay of Fundy, we have evidence in the wide extent of the same 

 formation in Prince Edward Island, that a similar deposit was in 

 progress in the Gulf of St Lawrence. In the gulf, however, unlike 

 the hay, we do not find the New lied along the coasts, hut in an 

 isolated patch separated on all sides from the continent. I may 

 remark here, that the New Red Sandstone, though patches of it are 

 scattered over several parts of North America, is nowhere very 

 extensive. To the southward of Nova Scotia it re-appears in Connec- 

 ticut, where it extends over a considerable area in the valley of the 

 river; and in New Jersey, -where another band commences that 

 extends a great distance to the south-east, some isolated patches 

 occurring as far south as North Carolina. 



The aqueous rocks of the New Red Sandstone period in Nova Scotia 

 and Prince Edward Island are principally coarse and soft red sand- 

 stones with a calcareous cement, -which causes them to effervesce with 

 acids, and contributes to the fertility of the soils formed from them. 

 In the lower part of the formation, there are conglomerates made up 

 of well-worn pebbles of the harder and older rocks. 



The volcanic rocks of this period are of that character known 

 to geologists as Trap, and are quite analogous to the products of 

 modern volcanoes ; and, like them, consist principally of Augite, a 

 dark green or blackish mineral, composed of silica, lime, and mag- 

 nesia, with iron as a colouring material. Various kinds of trap are 

 distinguished, corresponding to the varieties of modern lavas. Crystal- 

 line or basaltic trap is a black or dark green rock, of a fine crystalline 

 texture, and having on the large scale a strong tendency to assume a 

 rude columnar or basaltic structure. Amygdaloid or almond-cake 

 trap is full of round or oval cavities or air bubbles, filled with light 

 coloured minerals introduced by water after the formation of the rock. 

 This represents the vesicular or porous lava which forms the upper 

 surface of lava currents, just as the basaltic trap represents the basalti- 

 form lava which appears in their lower and more central parts. The 

 only difference is, that in the amygdaloid the cavities are filled up, 

 While in the modern lavas they are empty. In some old la\ 

 however, the cavities are already wholly or partially filled. A third 

 kind of trap, very abundant in Nova Scotia, is Tufa or Tuff, or volcanic 

 sandstone, a rock of earthy or sandy appearance, and of gray, greenish, 

 or brown colour. It consists of fine volcanic dust and scoria?, popularly 

 known as the ashes and cinders of volcanoes, cemented together into 



