288 W. H. HOBBS — GUADIX FORMATION OF GRANADA, SPAIN 



1,000 feet, mainly a conglomerate having distinctly water-worn pebbles 

 which vary from a fraction of an inch to six inches or more in length. 

 Interbedded within the formation are layers of fine sand and loess-like 

 material which changes most abruptly to the conglomerate. In the finer 

 material stratification shows plainly, and, while generally horizontal, dips 

 as high as 25 degrees occur; but these dips are in the narrow portions of 

 the valley and are apparently uniformly in the direction of its bottom. 



In ascending the valley of the Darro along the old post road from 

 Granada to Guadix, one sees grea/t thicknesses of the loess-like material, 

 and at other times merely thin layers a fraction of an inch in thickness 

 may be followed for many rods along a horizontal plane within the con- 

 glomerate. Not infrequently lenticular forms are noticed in the section. 

 A little above the village of Huetor-Santillan the Alhambra formation 

 comes into contact with the Upper Triassic dolomite of the Sierra Harana 

 to the north of the road. The Darro valley has now narrowed to such 

 an extent that the same dolomite soon appears upon the other side of the 

 valley as well and the Alhambra formation presently comes to an end. 

 Its steeper dips toward the valley are here noticeable, and the weathering 

 of the dolomite is most instructive in considering the origin of the 

 Guadix formation. Bising in steep slopes, the dolomite takes the form 

 of beetling crags whose divisional plains have been largely determined 

 by joints, while at the base of the cliffs is found an aggregation of larger 

 and smaller blocks already arranged imperfectly in trains along the bot- 

 toms of small gullies or barrancas. The first heavy shower will carry a 

 portion of these blocks down into the Darro valley, rounding the angles 

 on the soft material. An observation of von Drasche, made to the east 

 of the divide, is that the larger blocks are generally found near the bor- 

 ders of the formation. 



THE GUADIX FORMATION OF VON DRASCHE 



Passing over the divide between the Darro and the Farde near El 

 Molinillo and descending into the valley of the last mentioned stream, 

 after passing Diezma we obtain a view of the broad plain of Guadix, 

 which stretches away for 25 miles to the base of the Sierra de Baza and 

 appears as level as a floor. In this deposit of soft material the Farde 

 has cut broad valleys with level floors and steep walls, revealing abun- 

 dant sections of the material, which has characters in many respects the 

 same as those found in the valleys of the Darro and Genii. It is, how- 

 ever, as a rule finer in texture, with larger proportions of loess. This 

 loess is locally filled with roots and brush ("Noah's brush heap"), is yel- 

 low in color, and altogether quite similar to the loess of the upper Missis- 

 sippi valley. Throughout the loess is very perfectly jointed on vertical 



