On the Rocks of North Devon. 69 



and as this grew, it cut back into the reach above, and this in turn 

 cut back towards the head of the fans, and sometimes into the 

 trough. In some cases other secondary fans were formed on the 

 margin of the main fan, but the apparatus was not large enough 

 for further formations. The general slope of the fans, both pri- 

 mary and secondary, was -06, and that of the reach only -04, while 

 at the head of the reach, where it was cutting back into the face 

 above, there was a gradient of *08. 



The general tendency of the experiments supports not only the 

 specific conclusions as to the normal form and behaviour of a river 

 which has attained a state of equilibrium, but to a greater degree 

 the fundamental assumption that a river will adapt its channel to 

 such a slope and form as will enable it to just transport a solid 

 burden cast upon it. 



2. " On the Bocks of North Devon." By Henrv Hicks, M.D., 

 F.E.S., Sec.G.S. 



During a recent visit to North Devon the author obtained evi- 

 dence which has led him to believe that far too little importance 

 has hitherto been assigned to the results of movements in the 

 Earth's crust as affecting the succession of the rocks in that area. 

 The supposed continuous upward succession from the rocks on the 

 shore of the Bristol Channel to those in the neighbourhood of 

 Barnstaple, including, according to some authors, no less than ten 

 groups, and classed into three divisions under the names Lower, 

 Middle, and Upper Devonian, is, the author believes, an erroneous 

 interpretation. The beds, he says, have been greatly plicated and 

 faulted, and consequently several times repeated, and instead of 

 being one continuous series, they occur folded in more or less 

 broken troughs. In the Morte Slates, previously considered un- 

 fossiliferous, the author found a Lingula, and he believes that these 

 slates are the oldest rocks in the area, and formed the floor upon 

 which the Devonian Eocks were deposited un conformably. As the 

 result of movements in the Earth's crust, the Morte Slates have 

 been brought to the surface and thrust over much newer rocks, 

 producing a deceptive appearance of overlying the latter conformably. 

 The Morte Slates mark the dividing line between the two main 

 troughs. On the north side in ascending order are the Hangman 

 (or Lynton), Combe Martin Bay, and Ilfracombe Beds, and on the 

 south side the Pickwell Down, Baggy Point, and Pilton Beds. 

 Those on the south side of the Morte Slates are, the author 

 believes, a repetition of the beds on the north side. The palteon- 

 tological evidence is not antagonistic to this view, for an analysis of 

 the Brachiopoda, the only group of fossils in the beds on the south 

 side, which hitherto have been systematically examined, shows that 

 of the twenty species mentioned by Mr. Davidson and others as 

 occurring in the Pickweli Down, Baggy Point, and Pilton Beds 

 (the so-called Upper Devonian Eocks), no less than thirteen have 

 already been found in the Middle or Lower Devonian rocks on 

 the north side of the Morte Slates. Pour others are recognized 



