Page:The Journal of geology (IA journalofgeology11893univers).pdf/446

In the midst of the shales and greywackes of the Upper Kulm of Frankenwald, there is a peculiar sort of conglomerate (geröll-thonschiefer). This conglomerate is exposed at but few points. It is not certain that all the exposures belong to one horizon, though nothing is known which forbids this conclusion. The demarkation of the conglomerate from the underlying and overlying beds is sometimes, but not always, distinct. The conglomerate has a known thickness at one point of at least 18 m. It is wholly unstratified, and is made up of something like equal parts of clayey matter, and well-rounded stones (geröllen). The sand grains are conspicuously angular, while the larger stones are as distinctly well-rounded. In no case do the sandy or stony materials show any traces of arrangement suggestive of stratification. The stony material varies in size from pebbles to small boulders, the largest being 22 ✕ 29 ✕ 12 c. m. In connection with these limitations in size it must be remembered that the exposures are very limited. While it is difficult to determine the origin of the stony material in all cases, it does not seem necessary to suppose that it is of very distant origin. The author considers the various possibilities concerning the origin of this conglomerate, and concludes that it is the work of rivers which were affected by floating ice. The conglomerate is therefore an indication of cold climate in the adjacent regions at the time of its formation. The author thinks that the Carboniferous ice period, belief in which seems not to be without foundation, may be brought into connection with the cold climate indicated by this conglomerate bed in the upper Kulm. He further thinks that the cold climate of the Kulm may have made itself felt over wide areas, since more or less extensive conglomerate beds of this age occur in widely separated parts of the German Empire.