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sandstone, of tlie sand ; the marls, of the luud ; and by the changing sets of 

 currents, or perhaps of tides, or possibly of alternate rising and subsiding of the 

 surface of the bottom, these different beds are laid down every now and again, 

 and so appear and re-appear as exposed to us to-day. 



Meanwhile from time to time the feeding streams become charged with 

 lime, from the wearing away of some of the ancient limestones which they have 

 been washing in their course ; and then are laid down those concretionary strata 

 which I told you are called Cornstones. All the while, in the deepening lake, the 

 incumbent weight of water is solidifying the deposits, and hardening them into 

 stone. But there comes a time when, having reached its lowest temporary point, 

 the surface of the ground begins to be again elevated, and this elevation goes on 

 until when we come to the uppermost beds of the Old Eed, as you may see them 

 on the sides of the Glee Hills, the Scyrrid, the Blorenge, and Pen Cerrig Calch, 

 on the Usk, the conglomerates, composed of rough sand and pebbles, sometimes 

 of large size, or quartz and porphyry, bespeak a gradual shallowing of the 

 water up to a time when the hungry waves tore such fragments from their parent 

 rocks, or seized them as they fell, rolled them into pebbles, and scattered them 

 upon the lake's floor. 



So we have come to an end of the formation process of the Old Red, but I 

 would ask you to go a little further with me still. The Passage Beds from the Old 

 Red to the Carboniferous system tell us of shallow waters, as did those from the 

 Silurian upwards. Another subsidence of the earth's surface takes place, this 

 time under changed conditions ; so that what space w.as occupied up to now by an 

 inland lake is now covered by wide open sea. This time too the deepening of the 

 waters goes on to such an extent as to allow eventually of the formation of a great 

 rock surface of what is called the Mountain Limestone. Such limestone is not, so 

 far as is known, composed save at the bottom of deep seas. Once again, in 

 process of time, elevation takes place. The sea becomes shallower and shallower, 

 so shallow at last that the dry laud appears in great measure in its place ; and 

 then begins that condition of things, of climate, of disposition of land and water, 

 and so on, which allows of the growth of giant ferns, reeds, club-mosses, and 

 other kindred plants. These have left in their decay their abiding record in our 

 Coal beds : the dark-green — to refer to the map — has overspread the red. One 

 more remark as to this period of formation. You will recollect, please, that what 

 I have been speaking of has taken aii incalculable period of time to work itself 

 out. During that time the subterraneous forces of the earth have not been idle, 

 molten streams of volcanic origin have burst through the crust, and, as at the 

 Titterstone Clee Hill, have obtruded a great shaft of basalt, or, as at Bartestree, 

 near Hereford, have upheaved a mass of greenstone, or, as at Malvern, of granitic 

 rock ; earthquakes have been at work, pushing upwards lower beds, as in the famous 

 valley of Woolhoise; the crust of the earth has cracked and folded itself, either 

 from this earthquake expansion or from contraction and shrinkage from within ; 

 and the beds, which were of course originally laid down horizontal, have been 

 slanted, upraised, thrown down, so that, for instance, the beds of Upper Old Red 

 at Symoud's Yat, which, geologically speaking, are thousands of feet above those 



