Page:Quarterly Journal of the Geological Society of London, vol. 29.djvu/265

 rections in which water in equal volume would flow more swiftly. By this alphabet I will now try to spell out some of the ice-records on Irish rocks*.

1. Small mountain-glaciers. — In Norway, districts of varying area, from a patch as big as several Irish counties to a mere hill-top, still are covered by thick beds of snow and plastic glacier-ice. About Bergen long deep fjords a hundred miles long lead up to long deep glens, which are rock-grooves. These lead up to smaller branching glens of like pattern, of which some lead up to the ice-regions. The ice forms upon high plateaux. All these hollows are of one pattern. A section is like the letter U ; they have steep rocky sides ; and drift of sorts is packed in the grooves from the sea up to the ice. At the head of the Sogne Fjord in one of these long deep bare rocky grooves, about three miles from the sea and amongst cornfields, is a glacier called Supedledals Iis Brae. It is made of ice which falls from the ice-plateau down a steep rock-face. It falls in fragments, which " regelate " and form a pile which slides down into the glen, and shapes itself as any other plastic mass might do. It moves from the side of the U towards the centre ; and it draws marks at right angles to the run of the main stream, and to the ebb and flow of the sea in the fjord. But the movement of this side glacier is parallel to that of small streams, which trickle down the side of the rock-groove and join the main river in the bottom.

In Donegal, between Gweebarra Bay and Lough Veagh, a deep groove crosses Ireland from N.E. to S.W., with a col 750 feet high joining hills which are about 2500 feet high. On the northern side of this straight bare N.E. groove is a mountain called Slieve Snaght (snow mountain). On the other side is a hill of about the same height. About Lough Barra, which is close to the watershed, the rocks on both sides and in the bottom of the groove are smoothed and ground ; they are almost bare of vegetation : their structure can be seen as in a model ; and they are glaciated. Opposite to a cliff at the base of Snow Mountain are fresh ice-grooves in a roadside gravel-pit. They come from the cliff and go towards the lake and the river. It is therefore clearly recorded that an Irish glacier, like the glacier in Bergen, once existed in this Donegal pass, which is a miniature copy of a Scandinavian rock-groove.

Glaciers of this kind may be seen in mountain-districts where glaciers have decreased in size. Tracks of glaciers of this class abound in Kerry, in Connemara, in the Mourne Mountains, and elsewhere in Ireland. They all came down steep inclines from high points near the grounds where snow first appears in autumn and lingers the longest in spring, as it does upon Slieve Snaght, in Donegal, which a native unused to Celtic called " Sniff Snaff."

2. River-glaciers. — In the Bergen district above mentioned some of the upper branches of the main glens lead directly up to the

said. His own experiments and those which he describes, new and old, prove that glaciers flow and weld when broken. A set of prints, photographs, and sketches were produced with rubbings, taken by the author during many years.
 * Dr. Tyndall's book on the ' Forms of Water ' entirely confirms what is here