On the Topography of the Volcanic Zones in Iceland

Abstract

It has previously been pointed out by the present writer; that the Pleistocene volcanic zones of Iceland are not only a supramarine exposure of a part of the World Rift System, and as such much more accessible for geological, geophysical, and topographical research than the submarine parts of the system. The Icelandic zones are also the only supramarine part of the system where a relatively recent volcanic activity has taken place under water and thus under conditions similar to those on the submarine part. This water was meltwater from the overlying ice cover during those periods of the Pleistocene when the country was blanketed by ice. The basaltic magmas extruded in Iceland are similar enough to those of the submarine rift zones to make one expect similar shape and inner structures of the volcanic edifices built up. In both cases the formation of pillow lavas is a characteristic feature. The main difference in shape one may expect is that the subglacial edifices are likely to be somewhat more steepsided, being, at least in some cases, built up against walls of ice.