Geological Notes

Abstract

DEVONIAN ROCKS OF BELGIUM.—We have just received the first descriptive memoir issued by the Geological Survey of Belgium. It is a quarto pamphlet of some seventy pages by Prof. Malaise, containing an account of fossiliferous Devonian and Cretaceous localities. The author has been at work collecting his materials for more than twenty years, and he now publishes a list of 173 places in Belgium from which Devonian fossils have been obtained. These places are arranged stratigraphically, and the names of the fossils found at each are given. As a contribution to the local geology of Belgium the pamphlet will doubtless prove of service. It is evidently a piece of laborious and painstaking work, of the kind that ought to precede the broad generalised summaries which the Survey will eventually be able to present for the information of the world. There is attached to it an index map, on which each of the fossiliferous localities is marked with a coloured spot, to which is attached a symbol indicating its geological horizon. Though the map is not, in the ordinary sense, a geological one, it tells its story clearly, and will be a convenient guide to those who purpose to visit the fossiliferous sites among the Belgian Devonian rocks. Prof. Malaise prefixes to his statistics a short introduction, in which he traces the history of Devonian classification in his own country and gives the subdivisions of the Devonian system which his own labours have led him to adopt. He modifies Prof. Gosselet's arrangement, taking the Couvin shales and limestone with Calceola out of the Inferior and placing it in the Middle Devonian group, together with the Givet limestone, but leaving the shales with Spirifer cultrijugatus in the Lower. These shales he regards as containing a fauna transitional between that of the Lower and that of the Middle division of the Devonian system. Prof. Gosselet has observed that if the Couvin limestone is bracketed with that of Givet, we must also place there the limestone of Frasne, as was done by Dumont. But M. Malaise replies that Dumont's classification was founded on mere lithological considerations, and that we can now trace palæontological differences among these subdivisions. It is interesting to observe among his fossils from the Upper Devonian Psammites du Condroz some of the forms which occur in the Barnstaple and Marwood beds of Devonshire, with remains of fishes (Holoptychius nobilissimus) of the Upper Old Red Sandstone of Scotland, and of ferns (Palœopteris Hibernica) identical with those of Kiltorcan in Ireland.