C. Lloyd Morgan — Geological Time. 199 



The probable truth is, I submit, that the whereabouts of the 

 Ilfracombe limestone (= Eifler kalk) comes in again south of the 

 Pickwell Down sandstones, among the Pilton slates; but the Coral 

 polypes not having lived there, probably from deficiency of carbonate 

 of lime, and excess of muddy sediment, the Coral limestone is 

 absent, and naturally the Fauna is in the main distinct from that of 

 the Ilfracombe area, the only limestone of any consequence being the 

 Culm or Posidonomya limestone with which we set out. 



Hence, by quite a different road, we arrive at the same conclusion 

 as before, that is to say, that the Old Eed Sandstone of Pickwell 

 Down, etc., has been invertedly doubled up from beneath all the 

 rocks to which the term " Devonian " can be assigned. 



EXPLANATION OF PLATES V. AND VI. 



PLATE V. — The coast near Sharkham Point, looking west. [From a photograph by 

 Brinley, Totnes.] Foreground shows crushed and folded limestone, the 

 lowest beds of the great mass of Berryhead and Brixham (1* in PI. VI.) 

 Under these are reddish and dun-coloured slates crushed and cleaved. At the 

 farther point are contorted red sandstones and slates. 



PLATE VI. — Diagrams, Figs. 1 and 2, show the general relations of the rocks in 

 PI. V. to the coast section. Traps omitted. 



Fig. 1. Supposing the limestone (1) the highest rocks of the district, the view main- 

 tained in the text. 



Fig. 2. Supposing the limestone ( 1 ) to come between the groups (3) and (2*) above 

 it, and slates (2) of Mudstone Bay beneath it, according to the received 

 opinions of writers. 



4- The part 1* slightly enlarged. (4. Volcanic.) 



Fig. 3. View near Woolacombe, North Devon (described in the text). 



Note. — By tracing and retracing from my pocket-book sketch, the foreground has 

 somewhat lost in effect. The curve is rather under- than overdrawn. 



II. — Geological Time. 

 By C. Lloyd Morgan, F.G.S., A.E.S.M. 

 (Part II.) 

 (Continued from p. 162.) 



IN passing on to the consideration of the rate at which the various 

 strata were formed, it will be well, I think, to group the rocks 

 Tinder six heads. First, Mechanical deposits formed in deltas, 

 lakes, and estuaries; secondly. Mechanical deposits along the shore- 

 line, in large bays, or constricted seas, such as the German Ocean ; 

 thirdly, Chalk ; fourthly. Coral Limestone ; fifthly, Coal ; and 

 lastly. Volcanic Kocks. 



I. With regard to mechanical deposits, it is obvious that they are 

 the products entirely, or almost entirely, of subaerial denudation, 

 although in the formation of the second group marine denudation 

 aids to some extent. Our first duty, therefore, will be to gain some 

 notion of the rate at which the land is wasting away under the in- 

 fluence of the weather, of rain, and of rivers. This subject has been 

 carefully studied by Mr. A. Tylor, Mr, CroU, and Professor Geikie, 

 and the study has been productive of most interesting results. But 

 a slight study of the action of rain as an agent of denudation is 

 necessary to make obvious the fact that the soil is gradually, and 



