Fig. 262.—A hanging valley. East side of Lake Kootenai, B. C. All except the highest summits glaciated. (Atwood.)
Fiords.—A glacier descending into the head of a narrow bay may gouge out the bay to a very considerable depth, causing its head to recede. When the ice finally melts, the bay may be a fiord. Thus have arisen the glacial features of many of the fiords of high-latitude coasts, and many of the glaciers of those coasts are now making fiords ([Fig. 266]). Fiords also arise in other ways. Coasts indented by fiords are likely to be bordered by islands.
The positions in which débris is carried.—As a result of the methods by which a glacier becomes loaded, there are three positions in which the débris is carried: (1) the basal or subglacial, (2) the englacial, and (3) the superglacial. The material picked up or rubbed off from the surface over which the ice moves is normally carried forward in the base of the ice; while that which falls on the surface is usually carried in the form of surface moraines. In the former position the drift is basal; in the latter, superglacial. It is doubtful if much débris is moved along beneath (that is, strictly below the bottom of) the ice, though the movement of the latter would have a tendency to drag or urge along with it the loose material of its bed. If drift were carried forward in such positions, it would be strictly subglacial.
Fig. 263.—A hanging valley. The water falls (Bridal Veil) from a hanging valley. (Wineman.)
The basal load of a glacier is constantly being mixed with new accessions derived from ground over which the ice is passing, and this admixture tells the story of the work done by the bottom of the ice. The englacial and superglacial material, on the other hand, is normally borne from the place of origin to the place of deposition without such intermixture. It is a case of “local” versus “through” transportation.
Transfers of load.—While the origin of the load usually determines its position, exceptions and complications arise from the transfer of load from one position to another, and from the gradation of one horizon into another.
Fig. 264.—A non-glaciated hill. Dalrymple Island. North Greenland.