Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/219

 rocks between which it is at present found, and that to this intrusion is owing the high elevation of the limestone? But though the above facts should be considered as justifying the hypothesis of the active agency of the greenstone, and consequently its fluidity, I am by no means prepared to affirm that this fluidity was that of igneous fusion; for neither the sandstone, nor the limestone, nor even the crumbling clayey marl appear to me to have undergone the smallest alteration by the contact or close vicinity of the greenstone.

The bed which lies immediately below the limestone and greenstone is (as I have already mentioned) a soft, rather sandy slate-clay. Its colour is bluish-brown and greyish white, and some of the strata contain egg-shaped nodules highly impregnated with clay iron, in closing the impressions of marine remains. It is very shivery and easy of decomposition, passing into a tenacious blue clay. On the south of the Severn, along the bottom of Wenlock-edge, it may very distinctly be seen supporting the limestone, and, like this latter, rising west by north at an angle of about 8°; but on the north of the Severn, and especially in the vicinity of Little Wenlock and Steeraway, its place seems to be taken by the greenstone already described.

This bed rests upon another of considerable thickness composed of a fine-grained soft micaceous stone of a dirty bluish-green colour, passing into greenish-grey and ochre yellow. On inspection by the lens it is manifestly a fine-grained mixture of green hornblende and brownish felspar with numerous spangles of mica, and little or no quartz. It is composed of strata which are alternately massive and slaty, and in the latter the direction of the mica is strictly parallel to that of the bed. That part of the bed which lies to the south of the Severn is elevated at an angle of 37° rising N.N.W. and forms a ridge of considerable height in the parallel of the Lawley and Caer Caradoc, on which are situated the villages of Cardington, Church