114) THE OCEAN. 



During the greater part of the year, in high lati- 

 tudes, the process of congelation is always going 

 on at the surface of the sea. If the wind is high, 

 the crystals cannot readily unite into a solid form, 

 but form a spongy mass, called sludge ; when this 

 has become somewhat thick, however, the wind can 

 no longer act upon the water, so as to raise little 

 ripples upon it, and the sludge now begins "to 

 catch ;" but the swell prevents one uniform surface 

 being yet formed, and the consequence is, that small 

 rounded plates of ice are produced, called "pan- 

 cakes," the edges of which are raised slightly, by 

 the constant pressure of one against another. The 

 cakes in the centre of the freezing mass now begin 

 to adhere to each other, and thus a solid surface 

 is produced, which gradually extends both its dia- 

 meter and its depth. The individual pieces of which 

 such ice is composed are distinctly to be traced, even 

 when perfectly consolidated, and present an appear- 

 ance resembling pavement. But in calm weather, a 

 thin pellicle of ice is simultaneously produced over 

 the whole surface of the sea, and the formation of the 

 ice-field is much more direct and obvious. Sins^le 

 fields have been seen many leagues in length, and 

 occupying an area of several hundred square miles ; 

 being at the same time from three to six feet high, 

 and from ten to twenty deep. The waves produced 

 by storms break up these fields into smaller pieces, 

 called floes, and driving one against another with 

 violence, the edge of one is often lifted upon the 

 other by the force of the pressure, and hummocks or 

 hills, of various shapes and sizes, are raised upon 



