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34 LA GRACIOSA. 
upon so many objects, that one can hardly give an ac- 
count of the impressions which he receives. At every 
step he imagines that he finds a new production; and, 
in the midst of this agitation, he often does not recog- 
nise those which are most common in our botanical 
gardens and museums.” A fisherman, who, having 
been frightened by the firing, had fled from them, 
but whom the sailors overtook, stated that no vessels 
had been seen for several weeks. The rocks of this 
small island were of basalt and marl, destitute of 
trees or shrubs, in most places without a trace of 
soil, and but scantily crusted with lichens. 
The basalts are not columnar, but arranged in 
strata from 10 to 16 inches thick, and incline to the 
north-west at an angle of 80 degrees, alternating 
with marl. Some of these strata are compact, and 
contain large crystals of foliated olivine, often por- 
ous, with oblong cavities, from two to eight lines in 
diameter, which are coated with calecedony, and en- 
close fragments of compact basalt. The marl, which 
alternates more than a hundred times with the trap, 
is of a yellowish colour, extremely friable, very te- 
nacious internally, and often divided into regular 
prisms like those of basalt. It contains much lime, 
and effervesces strongly with muriatic acid. The 
travellers had not time to reach the summit of a hill, 
the base of which was formed of clay, with layers 
of basalt resting on it, precisely as in the Schneiben- 
berger Huegel of Saxony. These rocks were co- 
vered with hyalite, of which they procured several 
fine specimens, leaving masses eight or ten inches 
square untouched. 
On the shore there were two kinds of sand, the 
one black and basaltic, the other white and quartzy. 
