TRANSACTIONS OF THE SECTIONS. 71 
valley, and extend over the elevated plain to the north of that city. 
From the northern verge of this plain there is a gradual descent into 
the wide and fertile valley of the Ebro, where luxuriant vineyards and 
olive plantations cover a marly soil full of small gravel. The boun- 
daries of this portion of the valley appear to be oolitic limestone, which 
forms flat hills, of a sterile aspect. Near Zaragoza, the rock below 
the soil, whenever it appears, is a yellowish grey limestone, which Dr. 
Traill refers to the same formation. 
After crossing the Ebro at Zaragoza, the route to Fraga lies chiefly 
over a desolate plain, named Llafa de Santa Lucia, once under cul- 
tivation, but now abandoned to rosemary, thyme, and other aromatic 
plants on its higher portion, and only appearing green where water 
lodges in the hollows during the rainy season, and produces salsola, 
salicornia, and similar plants, which the peasantry cut and burn into 
barilla, in the months of September and October. ‘The whole soil 
is gypseous and saline; the pools are brackish or absolutely salt; 
and potable water over this region is so scarce, that at Bujaralos it 
was sold at sixpence per gallon. At Pefialba the author found hori- 
zontal beds of a limestone containing fresh water shells; but the 
relative position of these beds become very apparent at the abrupt 
termination of the Llafia, in the valley of the Rio Cinca. There he 
observed an upper stratum of a greyish limestone, containing nu- 
merous fragments of limnez and planorbes; then a second with fewer 
of these organic remains; both rested on beds of clay marl, contain- 
ing thin strata of snow-white fibrous gypsum, and thick beds of the 
same substance in an earthy state. He did not detect any chalk in 
this place; but he found here nodules of pure flint. The whole of 
these strata covered a reddish sandstone, which is exposed in the bed 
of the Cinca. These limestone beds he considers as tertiary ; and he 
traced similar formations to the other bank of the river, beyond the 
city of Fraga. The whole of this district he compared to the forma- 
tions of the Parisian Basin. 
Just beyond Fraga the traveller enters Catalufia; and near Lerida 
he meets with a gritty limestone, which at Bellock gives place to a 
calcareous farcilite; near Cervera this is succeeded by a limestone 
splitting into thin layers ; all which the author thinks may be referred 
to the tertiary period, as the soil is full of shells belonging to the 
genera limnea and cyclostoma, though in his hurried examination he 
did not detect them in the rocks. Cervera is at the extremity of this 
_ formation, and is built on a rock of secondary limestone, which forms 
the fundamental rock visible between that city and Igualada. The 
country is now finely broken into wooded hills and cultivated valleys ; _ 
but the limestone between Igualada and Esparaguerra gives place to a 
conglomerate, with a basis resembling ordinary sandstone which 
slightly effervesces with acids. This conglomerate is a considerable 
- formation, not only occurring in the plains, but forming hills, and 
covering the flanks, and constituting the lofty spiry ridge of Mont- 
gerrat. This rock forms thick beds, which in the defile of Martorel 
are seen, in the channel of the Lobregat, to rest directly on a glossy 
