Note 4 — Chapter VI · The Winter Night

This is what goes on away there in the north month after month and year after year. The ice is split and piled up into mounds, which extend in every direction. If one could get a bird’s-eye view of the ice-fields, they would seem to be cut up into squares or meshes by a network of these packed ridges, or pressure-dikes, as we called them, because they reminded us so much of snow-covered stone dikes at home, such as, in many parts of the country, are used to enclose fields. At first sight these pressure-ridges appeared to be scattered about in all possible directions, but on closer inspection I was sure that I discovered certain directions which they tended to take, and especially that they were apt to run at right angles to the course of the pressure which produced them. In the accounts of Arctic expeditions one often reads descriptions of pressure-ridges or pressure-hummocks as high as 50 feet. These are fairy tales. The authors of such fantastic descriptions cannot have taken the trouble to measure. During the whole period of our drifting and of our travels over the ice-fields in the far north I only once saw a hummock of a greater height than 23 feet. Unfortunately, I had not the opportunity of measuring this one, but I believe I may say with certainty that it was very nearly 30 feet high. All the highest blocks I measured—and they were many—had a height of 18 to 23 feet; and I can maintain with certainty that the packing of sea ice to a height of over 25 feet is a very rare exception.4