SOLIFLUCTION 109 



The slope consisted of a gigantic sheet of mire, of the consistency of por- 

 ridge, and to judge from the cracks which ran across it and all round it, the 

 entire mass was slipping slowly, though imperceptibly, down the mountain-side.' 



All the notes collected in the preceding pages deal with regions 

 of recent solifluction. But of jossil occurrences of the same kind 

 indications are to be found in the literature. 



In the southmost part of England, outside the area of maxi- 

 mum glaciation, there is widely distributed a peculiar kind of deposit 

 known by the name of "rubble drift," "head," etc., and consisting 

 "of a more or less coarse agglomeration of angular debris and large 

 blocks set in an earthy matrix."^ This kind of soil is described 

 from Cornwall and Devon, from the South Downs and from Guern- 

 sey, one of the Channel islands. According to the opinion of James 

 Geikie and other English geologists, these beds were formed prin- 

 cipally by solifluction as an extra-marginal facies of drift at the 

 time of the maximum glaciation. 



A deposit of the same kind is the massive breccia of Gibraltar, 

 described by Sir A. C. Ramsay and James Geikie. It is a rude 

 accumulation of angular fragments of limestone, of all shapes and 

 sizes, imbedded in a calcareous grit and earth. As to its formation 

 Geikie writes: "When the snow melted in summer, the rubbish, 

 becoming saturated, would move forward en masse, like the so- 

 called earth-glaciers of the Rocky Mountains, as described by 

 Hayden."3 



It is remarkable that there are two different horizons of lime- 

 stone breccias at Gibraltar, indicating two separate epochs of severe 

 climate. 



After hearing my description of the Falkland stone-rivers and 

 the explanation of them as a facies of the ice age. Professor Hogbom 

 called my attention to occurrences of the same kind in the Ural 

 Mountains. 



They are mentioned by Tschernyschew in Guide des excursions 

 des VII. Congrh geologique international, Vol. Ill, pp. 28, 29, when 

 describing the quartzite mountains in the environments of the mines 

 of Bakalsk: 



^Ibid., Vol. II, p. 286. 



2 Geikie, The Great Ice Age, p. 389. 3 Geikie, op. cit., pp. 599, 600. 



