Survey of Northeast Greenland. 405 
the walls of the latter are broken to pieces, fall into the crack and 
so contribute to facilitate the freezing of the water in the crack and 
to increase the horizontal pressure. Room must necessarily be made 
for the new ice forming in the crack, and this can only be done by 
the ice lifting and placing itself like an irregular wall, the tidal 
pressure ridge, on both sides of the crack (see Fig. 97). 
In this manner the originally floating ice along the outer wall 
of the crack is forced deeper down into the water and is made to 
stand on the bottom even at highest water, and so this part of the 
originally floating ice has now become part of the ice foot. The tidal 
crack under review ceases to act, and there arises, or rather has 
arisen long ago, a new tidal crack further out, where the same play 
and interplay is repeated. In this manner there may, in the course 
of the winter, arise several series of fairly parallel tidal cracks and 
tidal pressure ridges, and the ice foot may extend into a depth of 
water, which far exceeds the one corresponding with the maximum 
thickness of the floating ice. 
The conditions here described in skeleton form are though more 
or less pronounced, quite a common occurrence in fjords and sounds. 
Only in the very few localities where the beach slopes so evenly 
and gradually that the ice cannot be broken by the flood wave, do 
tidal cracks and tidal pressure ridges entirely recede. This is for 
instance the case in the interior of Hellefjord and on the coast of 
Peary Land, north of Kap Eiler Rasmussen. In both of these places 
there is furthermore such a large accumulation of snow that it quite 
conceals the low beach, and so in springtime renders it all but im- 
possible to determine the position of the coast line (see extract from 
diary and the footnote on p. 327). In the interior of Hellefjord this 
circumstance caused the coastline — most probably laid down by 
means of several snow-bare spots further inland — to be drawn too 
westerly, so that the innermost and last bight of the fjord became 
considerably greater than it should be, which error was discovered 
during my journey in the summer of 1912. 
Ås in the fjords tidal cracks and tidal pressure ridges are often 
met with along the outer coast, even in some of those stretches 
where I have indicated on the map that the drift ice reaches in to 
the shore. The explanation of this is that the irregular, strongly 
pressed-up drift ice often has a deep draught. Consequently, along 
the shore and following the outer contour of the shallow water, there 
is often a narrow belt into which the ice cannot float, and in this 
belt fjord ice forms with tidal cracks and tidal pressure ridges. On 
the outer coast of Germania Land, where numberless small bays and 
creeks alternate with points and headlands, the drift ice is often met 
