512 Gironicles of Science. [Oct., 



flanked by projecting masses of rock, from "which loose stones could 

 be readily hurled on an invading foe. The eastern ascent is the 

 main approach, but the entrance is so strongly fortified by project- 

 ing walls or bastions that it could readily have been defended from 

 above. 



In the upper rampart the vitrified stones occur intermixed with 

 others not affected by fire, and with loose sand and gravel. In the 

 lower, or outer wall on the south side, the fusion has been much 

 more complete, pieces of granite, gneiss, mica-slate, and quartz- 

 rock, with some bits of sandstone, being all fused together, Mr. 

 Anderson observed long strings of vitrified matter which had 

 poured down from the melted mass above among the loose materials 

 beneath. 



The writer has carefully examined similar vitrified forts in the 

 Sidlaw Hills, overlooking the valley of the South Esk. 



Bearing in mind the infusible materials of which these walls are 

 buUt, it seems almost incredible that a rude and savage race should 

 have resorted to the agency of fire to consohdate them. The heat 

 required even to vitrify the exterior of a mass of granite must have 

 been not only very intense, but such as would endure for many 

 days. In Craig Phadrich the fusion of the walls had penetrated 

 for 12 or 14 inches into the mass. 



In the ' Natural History Transactions of Northumberland and 

 Durham,'* the Kev. G-. Kome Hall investigates the origin of certain 

 Terraced Slopes in North Tynedale. These terraces occur in the 

 borders of the valley of the North Tyne and the river Eede, near to 

 the Koman Wall and Watling Street, and close to the sites of nu- 

 merous British camps. They have been examined by the geologist, 

 the military engineer, the practical agriculturist, and the archae- 

 ologist, and each, from his own particular stand-point, has traced 

 then* formation to widely different agencies. The author describes 

 and maps upwards of seven sets of these terraced slopes : four sets 

 near the village of Birtley ; two sets near Swinburne Castle, and 

 another series near Wall Camp Hill, &c. 



The terraces of Steel Burn are 400 yards long, about seven to 

 ten in number, and face to the south-west ; another set, ten in 

 number, are 150 yards long, and face the west. The next series 

 are seven to eight in number, each several yards in breadth, five to 

 seven feet in height, and face due south. Near Buteland House 

 there are six to seven terraces, three feet in height, and many yards 

 in breadth, facing west. Those near Birtley form nearly a rect- 

 angle, the western face being 300 yards long, the southern face 110 

 yards. The former has six ledges, with a shorter one inserted 

 midway, and the lowest not parallel. The terraces average tliree, 



* Part i., vf)l. iii 



