blocks) it is not the periodic phenomena which are especially important. The intense, nonperiodic 

 fluctuations of the sea level have a much greater significance, for stone pUes and individual stones 

 of earthwork embankments and pavements, which are frozen into the ice, are pulled from the 

 ground with a quick and significant increase of sea level. Serious damage to the hydraulic instal- 

 lations is caused also by the expansion of the ice cover during the spring through solar radiation 

 (thermal). 



As an example of the last type of damage, the authors cite the inclination of one of the light- 

 house towers in the region of the island of Kotlin. After the spring of 1926, the tower tilted 1° 30' 

 from the vertical, and toward March, 1927, the inclination of the tower reached 2° 07' in the same 

 direction. 



Minute observations were carried out on the basis of these investigations to explain this 

 phenomenon, and Barabanov and Richter arrived at the following conclusion. It appears that a 

 continuous ice field, with one of its boundaries attached to the shore, expanded with the increase 

 in temperature of the spring air, thus exerting strong pressure on such installations as the light- 

 house tower. The extent of the stress depended on the height of the structure, within the limits of 

 the normal thickness of the ice cover. This stress extended to significantly greater heights, with 

 the size of the piled-up masses of ice from the previous fall and winter periods. 



Fissures are extremely important in the construction of ice roads. The width of the thermal 

 fissures on Lake Baikal sometimes reached 2 m. In the laying of a winter railroad before con- 

 struction of the railroad circling the lake, the power in the formation was so great that the rails 

 were split. The coefficient of linear expansion of the ice was almost five times more than that of 

 iron. Bolts and fastenings were strewn in all directions, and the road was destroyed along some 

 ten miles. During the first days of construction, doubts arose as to the possibility of an ice road 

 across such a wide water stretch as Lake Baikal. 



As Bernstein notes, fissures which stretched almost parallel to the road for 10 m charac- 

 terize ice crossings. These fissures sometimes traverse the road at very small angles. They 

 have a width of 4 to 5 cm at the top and a depth of 40 to 50 cm. With temperature increase, they 

 are filled with melted water, which freezes with a subsequent temperature decrease. 



Bernstein explains the origin of longitudinal 'fissures as follows: The ice under the railroad 

 bed is always eventually cleared of the snow, thus becoming thicker than that in adjacent areas. 

 With a temperature decrease, the ice surface not covered by snow becomes colder more rapidly. 

 A difference in temperature, which also causes fissures, is thereby created. Bernstein notes 

 that though snow removal from the road advantageously thickens the ice, it nevertheless causes 

 detrimental longitudinal fissures. I do not believe that the thermal effect is the sole cause for the 

 formation of longitudinal fissures on ice crossings. Ice is thicker on crossings where the snow 

 has been removed; consequently, hydrodynamic forces raise the crossings. With the construction 

 of roads on ice, the weight (cross ties, rails, etc.) exert a downward pressure on the ice. If 

 these influences are not in equilibrium, it is understandable that the appearance of longitudinal 

 fissures is inevitable. Bernstein recommends snow removal from the largest possible area along 

 the tracks as one of the preventive measures against the damaging after-effects of fissures. 



In 1942, I examined fissures along the tracks of the railroad across the River Kuznechikh to 

 Archangel. The fissures were 10 m and 10 cm wide, with a funnel-shaped top. One had a mea- 

 sured depth of approximately 70 cm. The fissure was completely dry (the air temperature on this 

 day was about -20°) and ran along the section cleared of snow, inside the wooden structure of the 



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