BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 VOL. 17, PP. 285-294, PLS. 35~36 JUNE 25, 1906 



GTJADIX FORMATION" OF GRANADA, SPAIN 



BY WILLIAM HERBERT HOBBS 



{Presented, by title, before the Society December 29, 1905) 



CONTENTS 



Page 



Introduction 285 



Description of the Guaelix formation 287 



The Block formation 287 



The Alhambra formation 287 



The Guadix formation of von Drasche 288 



Origin of the formation 289 



Age of the deposits 200 



Torrential deposits of southern Italy 290 



Probable torrential origin of many sandstones and conglomerates 292 



Acknowledgment 294 



Introduction 



The fertile Vega of Granada and the great plain of Guadix lie re- 

 spectively off the western and northern flanks of the Sierra Nevada and 

 are separated from each other by the much lower Sierra Harana. Level 

 almost as a floor, on their borders their surfaces incline valleyward at 

 low angles, producing a topographic feature most common in Spain — the 

 filled valley out of which steep mountain ranges rise abruptly. The 

 material with which these valleys are filled merits a fuller consideration 

 than is here possible, but a record of somewhat hurried observations, 

 with conclusions drawn therefrom, may be of value, since they apply to 

 a region which has received but little attention from geologists. Von 

 Drasche, who visited the province more than a quarter of a century ago, 

 has furnished the best description of the deposits, a portion of which he 

 has relegated to three formations, namely, the Alhambra conglomerate, 

 the Block formation, and the Guadix formation.* In the Block forma- 

 tion, which occupies the valley of the Genii, he found Miocene fossils, 



* Von Drasche : Geologische Skizze des Hochgebirgstheiles der Sierra Nevada in 

 Spanien. Jahrb. d. k. k. geol. Reichsanst.. Bd. 29, 1879, pp. 93-122, pis. vii-xii. 



XXV — Bull. Geol. Soc. Am,, Vol. 17, 1905. (285) 



