538 
ELEMENTS OE GEOLOGY. 
taken place. The Clypeaster altus^ Spondyliis gcBderopus^ 
Pectunculus pilosits^ Cardita ecdyculata^ and several other 
shells, serve to identify this formation with that of the Ma- 
deiras, and Ancillaria glandiformis^ which is not rare, and 
some other fossils, remind us of the faluns of Touraine. 
The sixty- two Miocene species which I collected in the 
Grand Canary were referred by the late Dr. S. P. Woodward 
to forty-seven genera, ten of which are no longer represented 
in the neighboring sea, namely Corhis^ an African form, Hin- 
nites^ now living in Oregon, Thecidium ( Mediterraneum^ 
identical with the Miocene fossil of St. Juvat, in Brittany), 
Calyptrma^ Hipponyx^ Nerita^ Erato^ OUva^ Ancillaria^ and 
Fasciolaria, 
These tuffs of the southern shores of the Grand Canary, 
containing the Upper Miocene shells, appear to be about the 
same age as the most ancient volcanic rocks of the island, 
composed of slaty diabase, phonolite, and trachyte. Over 
the marine lavas and tuffs trachytic and basaltic products 
of subaerial volcanic origin, between 4000 and 5000 feet in 
thickness, have been piled, the central parts of the Grand 
Canary reaching the height of about 6000 feet above the 
level of the sea. A large portion of this mass is of Pliocene 
date, and some of the latest lavas have been poured out 
since the time when the valleys were already excavated to 
within a few feet of their present depth. 
On the whole, the rocks of the Grand Canary, an island of 
a nearly circular shape, and 6^ geographical miles diameter, 
exhibit proofs of a long series of eruptions beginning like 
those of Madeira, Porto Santo, and the Azores, in the Upper 
Miocene period, and continued to the Post-Pliocene. The 
building up of the Grand Canary by subaerial eruptions, sev¬ 
eral thousand feet thick, went on simultaneously with the 
gradual upheaval of the earliest products of submarine erup¬ 
tions, in the same manner as the Pliocene marine strata of 
the oldest parts of Vesuvius and Etna have been upraised 
during eruptions of Post-tertiary date. 
In proof that movements of elevation have actually con¬ 
tinued down to Post - tertiary times, I may remark that I 
found raised beaches containing shells of the Recent Period 
in the Grand Canary, Teneriffe, and Porto Santo. The most 
remarkable raised beach which I observed in the Grand Ca¬ 
nary, in the study of which I was assisted by Don Pedro 
Maiiiotte, is situated in the north-eastern part of the island 
at San Catalina, about a quarter of a mile north of Las Pal¬ 
mas. It intervenes between the base of the high clilF formed 
of the tuffs with Miocene shells and the sea-shore. From 
