AND PORTO SANTO. 19 



landing place, on my first arrival. This line of cliff, which extends 

 to the bay, or break, in which the town is situated, a distance of 

 about three-quarters of a mile, varies in height from fifty to one 

 hundred feet ; and its natural sections disclose additional features, 

 as you approach the isthmus of rock which forms the Pontinha. 

 At its western termination, or close to the ravine, we find the fol- 

 lowing section, raising our eyes from the base : — a yellowish tufa, 

 almost hidden by the large masses of basalt and tufa which have 

 fallen from above, seven feet of scorice, or cinder, ten feet of 

 yellow tufa, seven feet of scoriae, with narrow horizontal ribands, 

 or veins of tufa, six feet of red tufa, fifteen feet of compact colum- 

 nar basalt : all these beds are more or less horizontal, only varying 

 from that position by slips. As we walk to the eastward, the 

 section deepens gradually to about 100 feet, and the yellow tufa 

 at the base, becoming more exposed, discloses two horizontal bands 

 (varying from 2 to 3i feet) of angular, and more or less rounded, 

 fragments of pumice, the largest not exceeding the size of a walnut, 

 and inserted as thickly as possible in yellow tufa. A close view 

 would not have conveyed an idea of the appearance of tliis section 

 so clearly, as that which is adjoined to the present description, 

 plate 3 A, which was taken from the Pontinha, somewhat less than 

 half a mile distant, and is a faithful representation, not only of the 

 depth and outline, but of the colours of the beds or strata. I 

 found a poor family living in a spacious apartment, which they 

 had hollowed out of the yellow tufa, and which made a much 

 more comfortable dwelling than their ordinary habitations : the 

 peasantry frequently make cellars and out-houses in the scoriae. 

 Immediately after, or at about 600 yards from the Pontinha, the 

 upper columnar basalt is abruptly discontinued, not from having 

 been removed, but from this point being the eastern hmit of the 

 stream out of which this face, or section, has been created, and 

 from no other stream of this upper basalt having directed itself 



D 2 



