THE FROZEN SOIL. 47 



in a piece of turfy ground near Bogoslowsk (59 44' N. L.) 

 among the Ural Mountains on the road to the Turjin mines.** 

 We found pieces of ice at the depth of 5 feet, which were 

 embedded, breccia-like, in the frozen ground, below which 

 began a stratum of thick ice which we had not penetrated 

 at the depth of 10 feet. 



The geographical extension of the frozen ground, that is to 

 say, the limits within which ice and frozen earth are found 

 at a certain depth, even in the month of August, and con- 

 sequently throughout the whole year, in the most northern 

 parts of the Scandinavian peninsula, as far east as the coasts 

 of Asia, depends, according to Middendorff' s acute obser- 

 vations (like all geothermal relations) more upon local 

 influences than upon the temperature of the atmosphere. 

 The influence of the latter is on the whole, no doubt, stronger 

 than any other, but the isogeothermal lines are not, as 

 Kupffer has remarked, parallel in their convex and concave 

 cuives to climatic isothermal lines, which are determined by 

 the means of the atmospheric temperature. The infiltration 

 of Hquid vapours deposited by the air, the rising of thermal 

 springs from a depth, and the varying conductive powers of 

 the soil, appear to be especially active. 80 " On the most nor- 

 thern point of the European continent, in Finmark, between 

 the high latitudes of 70 and 71, there is as yet no con- 

 tinuous tract of frozen soil. To the eastward, impinging 

 upon the valley of the Obi, 5 south of the North Cape, we 

 find frozen ground at Obdorsk and Beresow. To the east 

 and south-east of this point, the cold of the soil increases, 

 excepting at Tobolsk on the Irtisch, where the temperature 

 of the soil is colder than at Witimsk, in the valley of the 

 Lena, which lies 1 farther north. Turuchansk (65 54' 

 JN . L.) on the Jenisei, is situated upon an unfrozen soil, 

 although it is close to the limits of the ice. The soil at 

 Ainginsk, south-east of Jakutsk, presents as low a tempera- 

 ture as that of Obdorsk, which lies 5" farther north ; the same 

 being the case with Oleminsk on the Jenisei. From the Obi 

 to the latter river the curve formed by the limits of the 



49 Gustav Rose, Reise nach. dem Ural, Bd. i, s. 428. 



50 Compare my friend, G. von Helmersen's experiments on the rela- 

 tive conductive powers of ditferent kinds of rocks (Mem. de I' Academic 

 de St. Petcrsbourg : Melanges Physiques et Chimifjues, 1851, p. 32). 



