Pro/". E. Hull — The Great Pleistocene Lake of Portugal. 105 



In the Zegenda of the Geological Map of Portugal the succession 

 ■does not materially differ from the above, and is as follows : — 



iModerno e quaternario (alluTial). 

 Lacustre superior. 

 Marino (Almada Beds). 

 Lacustre inferior. 



p , I Superior (Hippurite Limestone). 

 Oretaceo | j^f^^^^^^ 



Description. 



The Upper Tertiary (Lacustre superior) consists of fine white, 

 yellow, and red sands, with thin layers of rolled pebbles, nearly 

 horizontal and 100 feet in thickness, resting on 150 feet of coarse 

 ferruginous sands and gravel; no organic remains have been 

 observed in these beds ; but at a locality 1 5 miles from Verdelha, on the 

 north bank of the Tagus, the hills rising about 200 feet above the sea 

 consist of brown marl and soft rubbly limestone containing Lymncsa 

 longiscata (Sow.), and have been traced from Cartaxo to Santarem. 

 These are probably the uppermost beds of the lacustrine series, and 

 overlie the sands and gravels previously described. 



At Villa Franca a bed of marl occurs 50 feet above the Tagus 

 with Lutraria compressa, and near Villa Nova da Raiuha the same 

 shell occurs with Gardium edide, both now living in the estuary of 

 the Tagus near Lisbon; so that, as Sharpe observes, it is evident 

 that this part of the country has been upheaved at least 50 feet 

 within a comparatively recent period.^ The occurrence of these 

 shells indicates, as it seems to the writer, a local intrusion of the 

 sea- waters at an early stage of the " Lacustrine " period. 



The Almada Beds (Miocene). 



These beds are so named by Sharpe from the promontory on the 

 south bank of the Tagus, opposite the city of Lisbon, where they 

 are well shown in the sea cliff. They consist of marls and lime- 

 stones rich in marine fossils, and are considered by Smith to be 

 of Older Miocene age. Of the 124 species determined, 20 are new 

 and peculiar, and are figured and described by G. B. Sowerby,^ 

 51 occur in the Older Miocene beds of Bordeaux, 17 in the Falunes 

 of Touraine, 15 in the sub-Apennine beds, 8 in the Eocene of the 

 London and Paris Basins, and 35 are recent. Their claim to be 

 referable to the Miocene stage is thus clearly established. At Lisbon 

 they rest unconformably on the Cretaceous Limestone.^ 



Pliocene Beds not represented. 



It will be observed that the "Almada Beds " of Miocene age are 

 immediately succeeded by those denoted on the Geological Map of 

 Portugal as " Lacustre superior," and by Sharpe called " Upper 

 Tertiary Sands, etc." The relative position of these sands to the 



1 Sharpe, ibid., p. 138. 



2 James Smith, supra cit., pp. 410—423. 



3 The Almada Beds rest on the sands and gravels called "Lacustre inferior," but 

 .as they are unfossiliferous theii- geological age is obscure or unknown. 



