Page:Popular Science Monthly Volume 67.djvu/643

Rh some of these stones in Brittany were put in place, there has been a noticeable subsidence of the coast, so that now some are only revealed at low tide. On the island of Erlanic in the Gulf of Morbihan is half of a cromlech; the other half with the whole of another circle tangent to the first is under water. But this subsidence of the land since these monuments were built would not necessarily indicate any great antiquity, for appreciable movements of the earth's crust, producing changes in level, have taken place in this region in comparatively recent times.

Most of the monuments of Brittany, with the exception of the lechs, which are known to be comparatively recent, seem to be of unhewn stone and many undoubtedly belong to some part of the Neolithic period, while others belong to the bronze. Stonehenge has been satisfactorily determined to belong to the bronze age, from its apparent association with the barrows which surround it. An examination of many of these barrows has revealed many bronze instruments and ornaments and determined them as belonging to that age. Avebury is probably much older, consisting entirely, besides the earthwork, of unhewn menhirs, while almost all the stones of Stonehenge are trimmed and squared, and the great outer circle is furnished with oblong, squared capping stones. And more than this, the capping stones dovetail into each other and are secured on their supports by means of hollows on their under surfaces fitting over bosses on the supports.