1853.] RIBEIRO AND SHARPE — BUSSACO. 137 



There seem therefore to have been great changes in animal life in 

 the period between the Red Sandstone, and the Jurassic or Liassic 

 Limestone ; but while it may be doubtful whether these intermediate 

 beds should be referred to the Lower Lias, or to the upper part of 

 the Red Sandstone, they strengthen the probability that the Red 

 Sandstone below them must be referred to a period altogether distinct 

 from that of the Lias. 



New Red Sandstone ? or Gres Bigarre ? — The Red Sand- 

 stone which underlies and fringes the cretaceous and Jurassic district of 

 Beira* has been traced for twelye or fourteen leagues from the banks 

 of the Vouga, by Serdao and Coimbra, to the neighbourhood of 

 Thomar; and although it is sometimes concealed by more modern 

 sands and sandstones, it has been recognised as one formation. Its 

 mineral characters vary locally, but are in general the same, and re- 

 semble those of the Gres Bigarr^ of the French ; and although no 

 organic remains have been found in itf, the position it occupies places 

 this classification of it out of doubt. 



The Red Sandstone of Beira may be divided for convenience into 

 two stages ; an upper division less developed, in which light colours 

 predominate ; and a lower division, truly red, more extended, and of 

 greater thickness. 



The upper division consists of a more or less coarse sandstone of a 

 light green, white, or ferruginous yellow colour, with patches of green 

 and red, in beds one or two metres thick, separated by thin beds of 

 fine incoherent sandstone of the same colours : it contains silicates of 

 iron, magnesia, &c., small quartzose fragments, and incoherent cry- 

 stals and fragments of flesh-coloured felspar in an argillo-siliceous 

 cement : the stratification is often irregular, and it does not afford a 

 good building stone : it may be studied at Eiras and Brasfemias, 

 three miles N.N.E. of Coimbra, at St. Joze de Marianos, and the 

 back of the Botanic Garden at Coimbra, on the heights of the Campo 

 da Ceira, two and a half miles S. of Coimbra, and at Podentes, ten 

 miles S.S.E. of Coimbra. 



The lower division, or Red Sandstone properly so called, is more 

 variable in character, but a brick-red colour always predominates, 

 especially in the middle and lower portions. At Goza, Taipa, and 

 Eiral, on the left bank of the Mondego, it is at top a coarse sand- 

 stone of a light purple colour, in thin beds, separated by layers of 

 white shale ; the above passes into a finer brick-red sandstone with 

 some mica and a little hematite ; the red layers alternate with others 

 of green micaceous sandstone, but the whole is so coherent that it 

 may be cut into large blocks, and is extensively used for building- 

 stone ; this part of the series cannot be less than 50 metres thick : 

 at Villa Nova de Monsares and Moita, eight miles S. of the points 

 above mentioned, this sandstone is quarried for ornamental build- 

 ings ; below it is coarser and passes into a conglomerate. At Moita 

 the sandstone is psammitic, carbonaceous, and schistose. 



* Journal of the Geol. Soc. vol. vi. p. 160, 161, and p. 165, and Map, p. 136. 



t In a subsequent letter Senhor Ribeiro mentions that in the Red Sandstone 

 have been found Calamites of different species from those in the Carboniferous 

 beds below it. 



