Chapter xlvi

.)]

(_c_) _Rhyolites._--In the Antrim plateau a group of rhyolite bosses occurs, some of which have been claimed as superficial lavas. In some cases it can be demonstrated that they are intrusive, and in no instance can they be decisively shown to have escaped in streams at the surface. It is probable, however, that some of these bosses did actually communicate with the outer air, for between the lower and upper group of basalts in this plateau, bands of rhyolitic conglomerate occur which may indicate the degradation of exposed masses of rhyolite. The description of these Antrim bosses will be given in