TRANSLATIONS AND NOTICES 



GEOLOGICAL MEMOIRS. 



On the Tertiary Formations of Spain ; extracted from the '^ Anales 

 de Minas,"^w5/25Aec? hy the Bireccion general delRamo. Madrid, 

 1838-1846. 



Our knowledge of the geological structure of Spain is so slight, that 

 I have been induced to extract from the above-mentioned work such 

 portions as bear upon this subject connected with the tertiary forma- 

 tions of that country. 



The first paper to be noticed is one by D. Joaquin Ezquerra del 

 Bajo, on a portion of the South of Spain, in which he states that it is 

 useless to attempt making a geological map, inasmuch as even a good 

 geographical map of the Peninsula does not exist. 



Respecting the geological structure of the South of Spain, only 

 two small works had been published before 1838 ; the one by Colonel 

 Silvertop in 1836, entitled, " Geological Sketch of the Tertiary Forma- 

 tions of the provinces of Granada and Murcia ;" the other by M. Le 

 Play, a French engineer, who has published in the * Annales des Mines' 

 two memoirs, in which he gives the results of observations made on a 

 journey of three months in 1833. 



Tertiary formations of Andalusia. 



The form and configuration of the Mediterranean basin was very 

 different during the tertiary period from that which exists at present ; 

 the mountains of Granada and Ronda then rose up as islands out of 

 that tertiary sea. At a subsequent period the marine tertiary deposits 

 of Andalusia were disturbed by the eruption of volcanic rocks, the 

 effects of which were most sensible to the south of the Sierra de 

 Grenada, being hardly felt on the side of the Guadalqui\ir. The 

 rocks which occasioned these disturbances were doubtless the trachytes 

 so abundant between Malaga and Cape de Gatte, near which latter place 

 basaltic eruptions have taken place on a large scale. 



Besides these tertiary marine deposits, there exist also freshwater 

 deposits, which not only overlie the others, but preserve their horizontal 

 position, not having been disturbed by subsequent eruptions. This 

 is also the case with the vast freshwater tertiary deposits in the centre of 

 Spain, and is a proof that they belong to a more modern period. The 

 fossil shells found in them belong moreover to existing species, 



VOL. VI. PART II. B 



