Baza and Alhama. 75 



norbis limestone makes its appearance in the form of swelling 

 undulations, which constitute some of the highest points in the 

 ridge. It does not, however, extend equally over the surface 

 of the compact limestone upon which it rests : from its friable 

 nature it has been much affected by various external causes, 

 and in many places has disappeared. It is in horizontal strata 

 often several feet thick. 



B. Ravine above Alhama, and a Portion of the Basin to its 

 sonth-east, ifi the neighbourhood of the Villages of Arenas 

 and Jayena. 



The coral limestone seen immediately before entering AU 

 hama by the Velez-Malaga road, — the little escarpments of cal- 

 careous sandstone and fine conglomerates of a similar base within 

 the precincts of the village, — the alternating beds of the two, in 

 the descent from the latter to the bridge, and the appearance of 

 sandstone strata at the commencement of the succeeding ascent 

 on the road to Granada, have been already mentioned ; and it 

 has also been stated that a part of the village extends along the 

 left bank of the ravine, which confines the stream known by the 

 same name, for about two miles above, and which opens out in- 

 to a valley of denudation immediately below it. 



This ravine affords the greatest facility for observing, and 

 the finest example of this marine formation. Here the rivulet 

 flows between perpendicular escarpments nearly two hundred 

 feet high, which are entirely composed of the two rocks just al- 

 luded to, in horizontal alternating beds from three to nine feet 

 thick. The limestone is made up of what appear to be small 

 coral fragments, agglutinated together by a calcareous cement. 

 A small fragment of a shell, an accidental little pebble, or a mi- 

 nute piece of schist, are rarely imbedded in its mass. It is tena- 

 cious, offering considerable resistance to the hammer, and is of a 

 dull whitish colour, with a slight tinge, in some places approach- 

 ing to red, in others to yellow. The fracture is uneven, coarse- 

 ly and largely granular, exhibiting rarely the section of a coral 

 branch, spines of echini converted into carbonate of lime, a few 

 shining crystalline facettes, and some minute superficial cavities. 



