RAMBLES OF A GEOLOGIST. 329 



able clay, should, by accumulating there, bind the layer on 

 which they rest, as is the nature of ferruginous oxide, into a 

 continuous stony crust. Wherever this pan occurs, we find 

 the superincumbent soil doomed to barrenness, arid and 

 sun-baked during the summer and autumn months, and, from 

 the same cause, overcharged with moisture in winter and 

 spring. My friend Mr Swanson, when schoolmaster of Nigg, 

 found a large garden attached to the school-house so invete- 

 rately sterile as to be scarce worth cultivation ; a thin stra- 

 tum of mould rested on a hard impermeable pavement of pan, 

 through which not a single root could penetrate to the tena- 

 cious but not unkindly subsoil below. He set himself to 

 work in his leisure hours, and bit by bit laid bare and broke 

 up the pavement. The upper mould, long divorced from 

 the clay on which it had once rested, was again united to 

 it ; the piece of ground began gradually to alter its character 

 for the better ; and when I last passed the way, I found it, 

 though in a state of sad neglect, covered by a richer vegeta- 

 tion than it had ever borne under the more careful manage- 

 ment of my friend. This ferruginous pavement of the boul- 

 der-clay may be deemed of interest to the geologist, as a cu- 

 rious instance of deposition in a dense medium, and as illus- 

 trative of the changes which may be effected on previously 

 existing^ strata, through the agency of an overlying vege- 

 tation. 



I passed, on my way, through the ancient battle-field to 

 which I have incidentally referred in the story of the Miller 

 of Resolis. * Modern improvement has not yet marred it by 

 the plough ; and so it still bears on its brown surface many 

 a swelling tumulus and flat oblong mound, and where the 

 high road of the district passes along its eastern edge the 

 huge gray cairn, raised, says tradition, over the body of an 



* For this story see " Scenes and Legends of the North of Scotland," 

 chap. xxv. 



