sider that all of the blue veins have their origin in the stratified beds of snow and ice from which glaciers are born. Any person who has been close to an "ice-fall" on one of the principal Alpine glaciers, and observed the great séracs lurching forward, with the primitive beds remaining parallel, or nearly so, to the surface of the glacier, must feel that it is extremely improbable that the masses will be so re-compacted lower down as to "furnish us with distinct planes extending parallel to each other for considerable distances." It will be felt that some of the séracs will be so smashed up that the original structure will be got rid of; that others, which descend more gently, will remain intact, but will settle down with their beds more or less inclined to the horizon; and that it will be a very extraordinary chance if the dip of the strata of any two of the masses coincides within many degrees.
Upon these grounds I believe that many of the veins of the veined structure of glaciers are nothing more than the upturned layers of blue ice which are formed upon and between the beds of snow that are deposited in the higher regions.[1] I am far from thinking that the occurrence of the whole of the veins of blue ice which are found in glaciers should be accounted for in this way. I do not believe that the combinations of different varieties of ice that are found in glaciers, which have been referred to by various authors as the veined structure, can be accounted for in two or even in three ways. Avoiding disputed points, I will observe that there are at least two other modes by which many veins of blue ice are undoubtedly produced in glaciers.
First, by water freezing into crevasses. I have seen hundreds of crevasses in Greenland nearly full of water; never quite full: the water seldom came within two or three feet of the surface of the glacier. I have seen the entire surface of the water in such crevasses frozen and freezing. I have seen the water sometimes frozen solid at one end and remaining liquid at the other end; and in the walls of icebergs I have seen sections of crevasses that have been
- ↑ Sometimes, probably thickened by pressure.
