156 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 21, 



rocks of tlie countiy, that it is quite uncertain where we ought to 

 separate them ; and no good hne of distinction, either geographical or 

 stratigraphical, has been observed between these beds and the calca- 

 reous series north of Cintra. In fact it was only after my return home, 

 and when I had examined all the fossils, that I became aware of the 

 marked difference of age between them. In all my rambles while in 

 Portugal, it never occurred to me to draw any line between the two sets 

 of beds. 



On the other hand, these beds rest unconformably on the Jurassic 

 limestone of Monte Junto, and present a striking contrast to all the 

 Portuguese rocks of the oolitic period. We must therefore conclude 

 that the sandstones and limestone here described belong to the lowest 

 member of the subcretaceous series, which, following closely after the 

 Jurassic system without any intervening break like that caused in the 

 north of Europe by the intervention of the freshwater formation of 

 the Wealden, contains a large admixture of oolitic species. 



In comparing the Portuguese series of beds with that of England, 

 we can find no parallels in England for the coralline limestone and 

 associated beds of Alenquer and Torres Vedras, and must class the 

 whole of this part of the series below our lower greensand, yet above 

 our oolites, and thus perhaps as the marine contemporary of the 

 Wealden formation. If the Neocomian beds of the south of France 

 and Switzerland should hereafter be proved to be distinctly older than 

 the lower greensand of the north, which appears probable, we must 

 then refer these Portuguese beds to the Neocomian series : in the 

 mean time I have avoided using the term Neocomian, lest the beds in 

 question should be confounded with the lower greensand of England, 

 Germany, and the north of France, to which that name has been some- 

 times unfortunately applied, and which is I think more modern thaa 

 the Portuguese beds in question, 



Jurassic Series of Beds*. 



It has already been mentioned that the district covered by the sub- 

 cretaceous beds is broken through in many places by limestones be- 

 longing to the Jurassic or Oolitic period which rise miconformably 

 through the strata resting upon them. These Jurassic rocks occur 

 in difPerent parts of the country, forming independent lines of hills, 

 so that their relation to one another is nowhere seen, and their relative 

 age can only be deduced from the comparison of their organic remains. 

 It appears from such evidence that there are in Portugal equivalents 

 of nearly all the principal members of the oolitic series. I will de- 

 scribe them in the order of their supposed age, beginning with the 

 most modern. 



Chain of Limestone from Monte Junto to the Mondego. 



The Serra de Monte Junto, which lies nearly forty miles north by 

 east of Lisbon, is the southern termination of a chain of limestone 



* I use the term Jurassic in preference to Oolitic, because the limestones of 

 Portugal have rarely an oolitic structure ; and the latter term might lead to a mis- 

 construGtion as to the mineral character of the beds in question. 



