460 A. Someyvail — Base of the Keuper in 8. Devon. 



Conclusions. 



The sandy loam a is, in oiu* opinion, the equivalent of the marsh 

 clay present in so many of the sections of the Holocene alluvium 

 of the Thames, and without doubt is of the same origin — a land 

 surface liable to flooding, each flood adding to the thickness of the 

 deposit. The old stream was a tributary of the Thames, and it 

 probably flowed in the same course when bed a was deposited. 

 The age of this bed is certainly pre-Eoman. The gradual sinking 

 of the lower Thames Valley, which has been in operation since the 

 close of the Pleistocene period, at length enabled the influence of 

 the main stream to be felt, and the carbonaceous silt was deposited. 

 From the presence of Roman potterj'- in this latter bed it is evident 

 that this did not take place in pre-Roman times, and the deposition 

 of the bed was no doubt carried on for several centuries. Lastly, 

 we have the modern reclamation, the piling of the stream, and 

 finally the filling up of the stream course and the erection of 

 buildins:s. 



V. — On the Base of the Keuper in South Devon.^ 

 By Alex Somehyail. 



WHILE appreciating and agreeing with the valuable work done 

 by Dr. Irving and Professor Hull, dealing with the New Red 

 rocks of South Devon, as set forth in their papers on this subject 

 in the Quart. Journ. Geol. Soc.,- there is only one point in which 

 I differ from these authors ; it is in relation to the rocks forming 

 the base of the Keuper in this area. 



In the last of these papers both authors agree to regard certain 

 breccias occurring at the mouth of the river Otter, and again at the 

 mouth of the river Sid on its eastern side, as the basement beds 

 of the Keuper. 



The basement breccias of the river Sid section, as explained by 

 them, are the Otterton breccias again brought up, and repeated 

 by the fault which occurs at the Chit rock, where the sandstones on 

 the east side of the fault are brought up against the Keuper marls 

 on its west side. 



The breccias near the mouth of the Otter have been described 

 by Dr. Irving as calcareous or dolomitic breccias, or conglomerates, 

 which I think quite a correct description of these beds. This 

 description, however, certainly does not apply to the alleged breccias 

 on the left bank of the Sid, to which I shall presently refer. 



The Otterton bi'eccias or conglomerates have been traced inland 

 by Dr. Irving to various localities, all of which I have visited and 

 have found correctly described. The breccias in the inland localities 

 are, however, all along the strike of the Otterton Beds, and not in 

 any case, along the strike of the alleged breccias said to occur in the 

 Sidmouth section. 



1^ Eead before the British Association, Southport, Section C (Geology), Sept. 1903. 

 2 See Quart. Journ. Geol. Soc, vols, xliv, xlviii, and xlix. 



