202 Mr. Tate on Basaltic Rocks. 



eastward it appears at the Fame Islands, all of which, twenty- 

 five in number, are formed of columnar basalt ; one isolated 

 mass, like a monolith rises out from the sea, sixty feet in 

 height, on the south side of the House Island ; and three 

 other similar masses with columnar structure, standing apart 

 in the sea, on the south side of the Stapel Island, are im- 

 pressive objects ; on these numberless sea-fowl rest, build 

 their nests, and rear their young. The basalt here varies in 

 thickness ; where in greatest mass the depth is about ninety 

 feet. Among those islands there are marked effects, both 

 chemical and mechanical, of the action of the basalt on sedi- 

 mentary rocks ; in the gut, between the Stapel and Browns- 

 man, limestone, sandstone, and shales, ninety feet in 

 thickness, lie upon basalt, and are metamorphosed and tilted 

 up against a basaltic cliff. They consist of — 



Indurated sandstone immediately above basalt. 



Arenaceous shale, much indurated but fossiliferous. 



Chert or metamorphic shale, with a conchoidal fracture, 



sharp edges, very hard, and also fossiliferous. 

 Limestone very much altered, but varying in character ; cherty, 



compact and dark in one part, buff and magnesian in another, 



and in other parts red and crystalline. 

 Indurated or cherty beds abutting against the basalt and 



nearly perpendicular in position. 



Besides other organisms found in these beds, are Fenestella 

 plebeia, Sulcoretepora parallela, Spirifer glaber, Strophomena 

 crenistria, Productus Flemingii, Chonetes Hardrensis, Dis- 

 cina nitida, Lingula squamiformis , Amusium Sowerbyii 

 Nautilus globatus, and the interesting trilobite, Griffithides 

 Farnensis of which complete specimens, for the first time, 

 were found here. On the north side of the Brownsman 

 Island, a patch of metamorphosed shale is intercalated with 

 basalt ; and both limestone and sandstone, also metamor- 

 phosed, are in the channel between the Fame and Wedum. 

 These various beds are similar to those on the main land at 

 North Sunderland, and belong to the middle part of the 

 calcareous group of the Mountain Limestone ; they had been, 

 by the basaltic eruption, torn from the mass with which they 

 were originally connected, lifted up and squeezed into their 

 present abnormal position. 



A long space of five miles and three quarters intervenes 

 between Islestone and Farne, and the next appearance of 

 basalt on the south side of Beadnell Bay, near to Newton 



