Baza and Alhama. 73 



ley. Continuing to ascend, numerous little shining pieces of 

 laminar gypsum are observed, interspersed in this soil. The ac- 

 clivity gradually becoming steeper, cultivation ceases, except 

 here and there in small patches ; the tract begins to assume a 

 mountainous character, and the line of road inclining towards 

 the left or south, approaches the confines of this eminence with 

 the bounding ridge of the basin. Several escarpments, looking 

 like perpendicular sections in a quarry, were observed along the 

 higher part of the acclivity, and beyond these a long irregular 

 low parapet, bordering and circulating around the summit of 

 the hill. On approaching the former, they were found to ori- 

 ginate in workings for gypsum, and to consist of a series of ho- 

 rizontal layers or strata of this mineral, accompanied by marl. 

 These layers, or little strata, are from one to three inches thick, 

 and the escarpments from twenty to forty feet high. Tlie gyp- 

 sum is of a laminar structure, and confusedly crystallized, seve- 

 ral separate pieces of it being often joined together in all sorts 

 of directions, and imbedded in an argillaceous marl, which seems 

 to form about one-fourth of the mass of each layer or stratum. 

 On reaching the summit of the hill, about a hundred yards be- 

 yond these quarries, the little escarpment which runs along its 

 crest, was observed to be formed of thick horizontal strata of 

 compact limestone, in which moulds of paludinae are occasionally 

 seen. It is of a whitish colour, frequently marked by little den- 

 dritic sprigs : its fracture compact and even, sometimes ob- 

 scurely conchoidal. A considerable tract of table-land, where 

 this rock is every now and then seen to come to day, and co- 

 vered with a short herbage, underwood, and a few evergreen 

 oaks, extends as far as the eye can reach, in the direction of 

 Loja, and, towards the south, appears to abut against the higher 

 ridge of secondary limestone, which, as before stated, bounds 

 this portion of the basin. 



In the ascent from the bed of the ravine to the summit of 

 this hill, beds of four distinct characters have therefore been ob- 

 served, viz. 1. The nummulite secondary limestone ; % Strata 

 of calcareous sandstone and coral limestone; 3. A powerful 

 bed of gypsum; 4. Compact pal udina limestone ; and the ho- 

 rizontality* according to which they are arranged seems to 



• The slight dip of the secondary nummulite limestone would conduct it 

 under the tertiary strata of the hill. 



