In ordinary times, layers from six to eight feet deep are regularly added annually to the accumulation of snow in the higher regions--not taking into account, of course, the heavy drifts heaped up in particular localities, but estimating the uniform average over wide fields. This snow is gradually transformed into more or less compact ice, passing through an intermediate condition analogous to the slush of our roads, and in that condition chiefly occupies the upper part of the extensive troughs into which these masses descend from the loftier heights. This region is called the region of the _névé_. It is properly the birthplace of the glaciers, for it is here that the transformation of the snow into ice begins. The _névé_ ice, though varying in the degree of its compactness and solidity, is always very porous and whitish in color, resembling somewhat frozen slush, while lower down in the region of the glacier proper the ice is close, solid, transparent, and of a bluish tint. In consequence of the greater or less rapidity in the movement of certain portions of the mass, its centre progressing faster than its sides, and the upper, middle and lower regions of the same glacier advancing at different rates, the strata, which in the higher ranges of the snow fields were evenly spread over wide expanses, become bent and folded to such a degree that the primitive stratification is nearly obliterated, while the internal mass of the ice has also assumed new features under these new circumstances. There is, indeed, as much difference between the newly formed beds of snow in the upper region and the condition of the ice at the lower end of a glacier as between a recent deposit of coral sand or a mud bed in an estuary and the metamorphic limestone or clay slate twisted and broken as they are seen in the very chains of mountains from which the glacier descended. VOLCANIC ACTION --SIR ARCHIBALD GEIKIE Large quantities of water accompany many volcanic eruptions. In some cases, where ancient crater-lakes or internal reservoirs, shaken by repeated detonations, have been finally disrupted, the mud which has thereby been liberated has issued from the mountain. Such “mud-lava” (_lava d’aqua_), on account of its liquidity and swiftness of motion, is more dreaded for destructiveness than even the true melted lavas. On the other hand, rain or melted snow or ice, rushing down the cone and taking up loose volcanic dust, is converted into a kind of mud that grows more and more pasty as it descends. The mere sudden rush of such large bodies of water down the steep declivity of a volcanic cone can not fail to effect much geological change. Deep trenches are cut out of the loose volcanic slopes, and sometimes large areas of woodland are swept away, the débris being strewn over the plains below.