Geology and Physical Geography. 331 



tonnee), smoothed, and grooved. The grooves, and the clefts 

 in the crest of the hill, all lie in one direction, viz., directed 

 to a point to the north of east. There are also long hollows, 

 with rounded intervening swells ; and these run precisely in 

 the same direction. At various places between the hill and 

 the sea are seen sandstone surfaces, worn down to a remark- 

 able flatness and smoothness, and in several instances marked 

 with striae, all pointing in the same direction. 



Throughout the valley of the Forth, from the Pentlands on 

 the one side to the Fife hills on the other from Linlithgow to 

 Dunbar, the sandstone surfaces, wherever they come up, are 

 likewise smoothed, and in many instances striated, the striae 

 all pointing to the ENE., or thereby. The trap hills rising 

 in this valley are all long and narrow, generally free from 

 abruptness on the sides, often abraded on the west, and 

 generally sloping away gently to the east ; the direction here 

 also is always to ENE. Surfaces on the Pentlands and in 

 Fife exhibit striation precisely conformable. In short, if a 

 deep ice-flow passed through this valley, it might be ex- 

 pected to produce precisely the phenomena which have been 

 observed. 



The similar markings on other districts of Scotland were 

 ghewn for the most part, though not without striking excep- 

 tions, to be directed towards the east and south. 



Mr Chambers adverted to the theory of debacles, which 

 was started to account for these appearances, as now nearly 

 given up. Ice was generally acknowledged as concerned in 

 producing them, because the appearances were precisely 

 those which the existing glaciers produce. But there was 

 great room for speculation as to the circumstances under 

 which the presumed glacial agent was applied. Mr Chambers 

 declined theorising on the subject, but pointed out various 

 conditions which any theory on the subject must explain. 

 (1.) How ice could move over so large a portion of the North 

 American continent, in a direction admitted to be tolerably 

 uniform, allowing for slight deviations easily explicable, as 

 owing to inequalities in the original surface, and without any 

 mountain chain to give it forth. (2.) How this ice was 

 capable of ascending slopes and topping mountains many 



