148 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoY. 21, 



than those of Figueh'a and Buarcos, and with Jurassic limestones more 

 modern than those of Cape Mondego. We must therefore presume 

 that there is a complete break in the series at the line where the dip 

 changes on the west of Buarcos, although the aspect of the country 

 does not indicate any great change, and the sandstones on the two 

 sides of the line of fault are not of very different character ; and that 

 this is a case, of which we shall meet other examples, where the resem- 

 blance of sandstones and sands of different ages, but in close contact, 

 makes it difficult to draw the exact line between two formations, the 

 difference of which is sufficiently marked at a moderate distance from 

 the line of junction. 



If we review the whole extent of the subcretaceous beds on the 

 north of the Mondego, we see that (except near Figueira) they usu- 

 ally strike from N.N.E. to S.S.W. with a very slight dip to the 

 W.N.W. : guided by this clue and by the light afforded by the or- 

 ganic remains, we may class the beds roughly in the following de- 

 scending order : — 



Sand : in all the N.W. part of the district. 



Sand and loose sandstone with alternations of thin beds of Umestone, 



in which the commonest fossil is the Exogyra conica. 

 Sands and sandstone. 

 Limestone of Sarjento-mor, San Fagundo, Condeixa, and the hill west 



of Montemor, abounding with various species of Tylostoma, &c. 

 Red sands and red marls, round the Coimbra hmestone. 



The above form a connected series ; below these we must place the 

 following, leaving it doubtful whether there is any gap in this part of 

 the series : — 

 Limestone of Figueira, with Gryphcea columha and numerous other 



fossils. 

 Sandstones and grits between Figueira and Buarcos. 



These include all the subcretaceous beds seen on the north of the 

 Mondego. 



Near Coimbra the various formations cross the Mondego with only 

 a slight derangement of their course ; and I have already described the 

 continuation of the subcretaceous beds to Condeixa : to the west of 

 the latter town they are separated from the great western expanse of 

 the formation by a chain of Jurassic limestone which reaches con- 

 tmuously for above sixty miles from near the Mondego to Monte 

 Junto, about forty miles north of Lisbon, which will be described in 

 its place. I did not follow the beds to the eastward of this chain 

 below Condeixa, nor did I examine the hills along the south bank of 

 the Mondego. 



From the mouth of the Mondego opposite Figueira to Leiria, the 

 road crosses a great extent of ferruginous sands and loose sandstones 

 with very few beds of limestone, the whole covered by a considerable 

 deposit of coarse gravel, which is both coarser and more abundant 

 near the sea and dimhiishes as we proceed inland. This is a dreary 

 district principally covered by barren heaths or pine woods. The 

 beds are nearly horizontal with occasional changes of dip. This ap- 



