Page:A book of the Cevennes (-1907-).djvu/246

170 There were other inscriptions, but they have been mutilated. Chilhac stands on a rock composed in the lower portion of beautiful prismatic columnar basalt, capped with an amorphous flow. It is curious how sharp the line of demarcation is between the two beds. The situation is pretty, the church Romanesque.

The course of the Allier above Langeac presents many faces like organ fronts of basalt; in places the pillars form a pavé de géants. The prisms are employed along the roads to mark distances, and might easily be supposed to have been specially cut for the purpose. But all lava does not crystallise into prisms; under pressure it does. When not squeezed by super-incumbent beds it is cinderous. But there is another form it assumes, that of phonolith or clinkstone, flakes that can be cut like slates and divided into laminae. As slates they are employed extensively in Velay. But why the ejected lava should form films here and prismatic pillars there, I do not comprehend.

At Monistrol d' Allier the Ance du Sud comes in from the Margeride after traversing a picturesque gorge. Here may be studied a fine basaltic face, called Escluzels. There are grottoes in the neighbourhood excavated in the tufa by the hand of man, but when is not known. A chapel dedicated to the Magdalen has been scooped out of the rock, but given a frontage of wall, and is an object of pilgrimage on the Sunday following July 22nd, when and where may be seen some of the costumes of the neighbourhood not yet wholly discarded.

On the opposite bank of the Allier is S. Privat, where the stream of Bouchoure comes down writhing between high precipices. The tower of Rochegude occupies the