342 Colonel Silvertop ow the Lacustrine Basins of 



escarpment and the stream, or Rio de Baza, subsequently de- 

 scends to a horizontal tract, contiguous to the left bank of the 

 latter. A white farinaceous efflorescence, which has a bitter 

 taste, is often observed upon the surface of patches of ground, 

 which have remained for a considerable time unploughed, or in- 

 vesting the banks of little channels of irrigations, as well as va- 

 rious wild maritime plants. Some projecting low eminences and 

 hillocks, formed of horizontal strata of marl, with imbedded 

 gypsum, the former in a semi-indurated stale, and of a whitish- 

 grey colour, the latter in separated pieces, and of a laminated 

 structure, are observed rising to twenty or thirty feet above the 

 level of the surrounding tract. Here, therefore, along the line 

 of road which crosses the basin from Baza to Huescar, the gyp- 

 siferous marl is first distinctly seen, and hence to the latter 

 town it continues almost without interruption. 



About eight miles from Baza the road crosses the little stream 

 of the same name, confined by low escarpments of marl, and, 

 after a short gradual ascent, where numerous rolled fragments 

 of red sandstone strew the ground, passes through an aperture 

 in a sort of embankment, formed of alternating strata, of a gra- 

 velly conglomerate and marl. It then traverses a little hollow — 

 a sort of a valley of denudation in the gypsiferous marls — and, 

 after a subsequent ascent, whence onwards the nature of the 

 deposit may be constantly observed, enters upon a table-land 

 tract, which, varied or.indented by frequent little' hollows and 

 denuded spaces, extends to a village called Benamaurel, about 

 half-way between Baza and Huescar. One of these natural ex- 

 cavations of considerable magnitude, is crossed immediately be- 

 fore entering the last-named village, situated upon the summit 

 of the opposite ascent. I may here observe, that, from the ri- 

 vulet, or Rio de Baza, to Benamaurel, a distance of about eight 

 miles, gypsum is continually seen in every little natural section 

 of the horizontal marl strata over which the road proceeds. 

 This tract consequently presents a general even surface, inter- 

 rupted occasionally by little hollows of denudation, unwatered by 

 any stream, and a scanty vegetation of wild plants and shrubs. 

 But between Baza and the ford where the rivulet was crossed, 

 the gypsiferous marls were only observed in a few projecting low 

 eminences or hillocks, in the horizontal tract along its left bank. 



