44 8 SCIENCE PROGRESS. 



Almaro-em consist of sandstones at the base and summit 

 and limestones in the middle, the respective development 

 of the sandstones and limestones varying greatly. The 

 Cenomanian Limestone consists of compact limestones with 

 some marly limestones and sometimes with beds of flint. 

 They contain Rudistes Sphaerulites, etc. 



In the country of Bellas, which lies only 5 km. farther 

 east, sandstones are much more developed, and form not 

 only the Aptian but also the whole of the Valanginian. 

 Twenty kilometres north east of Bellas the sandstones 

 invade all that lies below the Bellasien. This is the case 

 also at Torres Vedras and Cereal ; and farther north still, 

 sandstones form nearly the whole of the Cretaceous. 



As far north as Torres Vedras there is no gap between 

 the Jurassic and Cretaceous; but beyond this point the base 

 of the Cretaceous is absent, and the gap becomes greater 

 as we proceed farther north. 



In general the coarseness of the material diminishes 

 towards the west ; and from this and the other facts noticed 

 we may conclude that in the region north of the Tagus, 

 during the Cretaceous period land lay towards the north 

 and east, and gradually sank, the sea attaining its greatest 

 extension in Cenomanian times. 



In the extreme east of Algarve the lower part of the 

 Cretaceous (the Neocomian of many authors) is entirely 

 marine. At S. Joao-da-Venda it is replaced by sandstones 

 and conglomerates ; while in Western Algarve it is en- 

 tirely absent. Here again then, as in the Jurassic period, we 

 find that land lay in Western Algarve during a considerable 

 part of the time while the eastern part of the province was 

 under the sea. 



Since both the Cretaceous and Upper Jurassic of 

 Portugal consist largely of shore deposits, it is not astonish- 

 ing that numerous beds of lignite have been discovered in 

 them, and that plants are very abundant. These have 

 been described in detail by Saporta, who finds a gradual 

 passage from the Jurassic to the Cretaceous flora without 

 any sudden change such as is met with in other parts of 

 Europe (40). 



