130 Reports and Proceedings — Geological Society of London. 



(1) The Lowlands are practically conterminous with the Tertiary 

 deposits, among which apparently Eocene, Miocene, and Pliocene 

 rocks are represented. The last-named consist of shelly sands 200 

 to 300 feet thick, gradually rising to a height of 700 feet south 

 and east of Saffi. Their surface is often covered with the slaggy 

 tufaceous crust described by Maw. The local presence of this 

 crust and the porous character of the deposit elsewhere have pre- 

 served it from denudation, and thus (in the opinion of the author) 

 its surface still presents the appearance of the Tertiary sea-bed on 

 which it was formed. Certain quarry-like pits, one of which 

 contains a pillar of white crystalline calciuna carbonate, are supposed 

 to be due to the explosion of steam connected with the existence of 

 hot springs. 



(2) The Plateau is underlain by three rock - formations : — 

 (a) Metaraorphic rocks including clay-slates, which probably under- 

 lie the whole Plain of Morocco and rise into a group of rugged hills 

 called the ' Jebelet,' in contradistinction to the ' Jebel ' or Atlas 

 proper, (h) The Lower Cretaceous rocks, consisting of red shales 

 and sandstones, the former frequently giving rise to brine springs 

 and containing salt-deposits at Demnat in the Atlas, (c) The Upper 

 Cretaceous rocks, chiefly white and cream-coloured limestones, which 

 attain their greatest development on the Plateau. 



(3) The Atlas itself is made up for the most part of the same 

 rocks. There is a core of metamorphic rocks, which is better 

 developed and wider at the western end of the range and narrower 

 towards the east. Next comes the great development of the Lower 

 Cretaceous strata, followed by a diminutive representative of the 

 Upper Cretaceous rocks. These rocks are much broken by folding 

 and faulting, and their structure is displayed in several sections 

 taken across the range from Demnat westward. The first signs of 

 glacial action were met with at Titula, consisting of moraine-like 

 heaps of debris ; elsewhere, scratched stones were found. The 

 Boulder-deposits described by Maw were not seen either east or 

 west of the locality described by that author ; but Maw's original 

 section was not ti'aversed, and the present author does not offer any 

 opinion as to the origin of the beds. Intrusive basalts penetrate the 

 Cretaceous rocks, while porphyrites, diorites, and other igneous rocks 

 pierce the metamorphic rocks of the central core. 



IL— February 1, 1899.— W. Whitaker, B.A., F.E.S., President, in 

 the Chair. The following communications were read : — 



1. "On Radiolaria in Chert from Chypon's Farm, Mulliou 

 District (Cornwall)." By Br. G. J. Hinde, F.R.S., F.G.S. 



This paper describes the discovery of a bed of chert on the 

 mainland, similar to that already described from Mullion Island. 

 It was found in 1877 by Mr. Howard Fox at Chypon's Farm. 

 Although detached blocks had been noticed in the fields, the rock 

 had not been previously observed in sitii. The chert is interbedded 

 with clay-slates, and it is a dark massive rock much traversed by 



