of Baza and Alhama. 83 



plateau^ which belongs, in physical geography, to the elevated 

 plain of La Mancha. The upper stratum here consists of a 

 bed of reddish gravel, probably of diluvian origin, which con- 

 ceals the subjacent limestone ; the latter, however, is well dis- 

 played in a quarry near, but before arriving at, the village of 

 La Gineta. It is of a compact texture, somewhat vesicular, 

 of a whitish-grey colour, and contains a ievf paludina?. 



From this point to Ocana, nine leagues from Madrid, the 

 plateau maintains nearly the same general level, with occasional 

 undulations, with the exception of a narrow low ridge of second- 

 ary (?) limestone near the village of La Mota, and an insulated, 

 outlying hill of red sandstone near a village called Molar *, a 

 name probably derived from the grinding-stones which the lat- 

 ter rock usually produces. With these two exceptions, no rock 

 is seen in situ from La Gineta to Ocana. The superior stra- 

 tum is almost universally of a marly or gravelly nature ; but 

 now and then a low eminence, or little hillock of puddingstone, 

 or a few thin discontinuous strata, of an earthy whitish marly 

 limestone, are observed by the side of the road. In passing 

 through the village of Roda, I remarked that several of the 

 houses were built of a compact whitish-grey vesicuW limestone, 

 which is, no doubt, met with in the immediate neighbourhood, 

 as it would be a rare occurrence in this part of the country to 

 bring such materials from any distant point. 



At Ocana, which may be considered as the northern termi- 

 nation of the plateau of La Mancha on this line of road, a ami- 

 lar limestone, in the form of an irregular low escarpment, bor- 

 ders the crust of the long slope from this elevated plain to the 

 river Tagus ; and in the descent to the latter, a powerful bed 

 of gypsum is observed in horizontal strata, accompanied by 

 varying proportions of marl. Between the Tagus and the river 

 Jarama, which enters the former a little below Aranjuez, the 

 road to Madrid passes over a level tract, occupied by the plan- 

 tations, gardens, and pleasure grounds, belonging to the royal 

 palace at Aranjuez, — and then, crossing the latter river by a 

 handsome bridge, called Puente de la Reyna, and traversing a 

 little flat on the opposite or right bank, ascends a considerable 



• Piedra de Molar, is the Spanish expression for a grinding-stone. 



r 2 



