30 A nj:w floka of 



in different parts of its course ; indeed it cuts across tliese strata 

 in some places, and alters its relative vertical position to the 

 extent of 1000 feet. 



There appeal's, however, to have been more than one eruption, 

 though probably succeeding each other at no great intervals of 

 time : Stanhope, Kirkwhelpington, Eatcheugh, and other places 

 give evidences of this. At Eatcheugh there may have been three 

 eruptions, but two pseudo-strata are distinctly seen there ; one 

 of them is wedge-shaped, and, in the course of 500 yards, dwin- 

 dles down from 90 feet to 30 inches in thickness, while the second 

 mass overlaps the other and is separated from it by 22 feet of 

 intervening limestone and shale. In a pit-sinking at Long Dike, 

 in search of the Shilbottle coal, two layers of basalt were passed 

 through ; one, 1 5 feet thick, is between metarnorphosed arenace- 

 ous beds ; and the other, 63 feet lower down, and 2^ feet thick, 

 penetrates, metamorphoses, and partly replaces a seam of coal. 



2. Another mass of trap rock, a greenstone or diorite of con- 

 siderable thickness, caps the Carter Fell at the height of 1600 

 feet above the sea level overlying Mountain Limestone strata, 

 which rest on the upturned edges of Cambro-Silurian rocks. 



BASALTIC VERTICAL DIKES. 



Besides the great lateral dike or dikes, a considerable number 

 of basaltic dikes cut through the Carboniferous strata nearly per- 

 pendiculax-ly, most of them having a direction from eastward to 

 westward. The character of the rock of nearly all of them is 

 similar to that of the Whin Sill, but generally finer in the grain, 

 and with the structure more altered by contact with stratified 

 rocks ; for at such points there is a mutual transference of cha- 

 racter, the basalt itself imbibing, as it were, a portion of the 

 mineral ingredients of the adjoining stratified rock. Of the fol- 

 lowing lasaltio dikes we have some definite information. Our 

 list begins with the most northern. 



The Cornhill I)ilce is seen in a cliff on the south bank of the 

 Tweed, half a mile below Coldstream Bridge, cutting perpendi- 

 cularly through the Tuedian beds with a direction of north 82° 



