Mr. Tate on Basaltic Rocks. 201 



the basalt; and beyond the fissure a metamorphosed shale 

 overlies the basalt. Section 3 shews these relations. 



Further southward, sandstone is above the limestone, and 

 both are enclosed within the basalt. And in such relations 

 do the stratified rocks appear, here and there, along this 

 coast till we reach a great fault, affecting both the basalt and 

 the sedimentary beds at the Harkar Rocks. By this fault 

 the rocks are so shattered and tossed about and intermingled, 

 that a section of them is very complicated. In the axis of 

 disturbance is a basaltic dike, having a direction of E. by N. 

 to W. by S., and a breadth of from three to five feet, but 

 widening as it descends. From this axis the beds dip away 

 on both sides at high angles — on the north side E.N.E., and 

 on the south side S.E., in some parts 80°. Basalt is on both 

 sides of the fault ; the internal forces having lifted up and 

 broken through the basalt as well as the sedimentary beds. 

 Sections 4 and 5 shew the disturbed condition of the rocks, 

 and the intermingling of the basalt with the strata. 



At the point of junction between the basalt and the shale, 

 quartz crystals, hexagonal prisms with pyramidal termina- 

 tions, some pale yellow and others red, have been formed on 

 the under surface of the basalt. 



Southward of this fault, the basalt undulates along the 

 shore as far as Bamburgh boat-house, and is here and there 

 overlaid by metamorphosed shales, which also fill up fissures 

 in the basalt. After a short break the columnar basalt re- 

 appears in the high isolated hill on which stands Bamburgh 

 Castle. It has been ascertained, from the sinking of a well 

 to supply the Castle with water, that it is 75 feet thick, rest- 

 ing on sandstone and shale, which are also seen on the west 

 escarpment of the hill. 



Before leaving this neighbourhood, it may be noted, that 

 the basalt is here sometimes amygdaloidal, the cavities being 

 usually filled with calcareous spar ; and that when in con- 

 tact with limestone it becomes more or less calcareous, while 

 the sedimentary rocks assume some of the features of basalt ; 

 so that there appears a mutual transfer of their respective 

 characters. Metamorphism is everywhere seen, the sand- 

 stones being indurated and burnt looking, limestones 

 crystalline, and sometimes specked with iron pyrites, and 

 shales converted into jasper and felstone. 



Half a mile southward of Bamburgh Castle, the basalt is 

 at Islestone on the shore and extending into the sea ; and 



2c 



