LOWER MIOCENE VOLCANIC ROCKS. 
539 
this beach, at an elevation of twenty-five feet above high- 
water mark, and at a distance of about 150 feet from the 
present shore, I obtained more than fifty species of living 
marine shells. Many of them, according to Dr. S. P. Wood¬ 
ward, are no longer inhabitants of the contiguous sea, as, for 
example, Stromhus huhonius^ which is still living on the West 
Coast of Africa, and Cerithium procerum^ found at Mozam¬ 
bique ; others are Mediterranean species, as Pecten Jacobmiis 
and P, polymorphus. Some of these testacea, such as Cardita 
squamosa^ are inhabitants of deep water, and the deposit on 
the whole seems to indicate a depth of water exceeding a 
hundred feet. 
Azores. — In the island of St. Mary’s, one of the Azores, 
marine fossil shells have long been known. They are found 
on the north-east coast on a small projecting promontory 
called Ponta do Papagaio (or Point-Parrot), chiefly in a 
limestone about twenty feet thick, which rests upon, and is 
again covered by, basaltic lavas, scoriae, and conglomerates. 
The pebbles in the conglomerate are cemented together with 
carbonate of lime. 
Mr. Hartung, in his account of the Azores, published in 
1860, describes twenty-three shells from St. Mary’s,* of 
which eight perhaps are identical with living species, and 
twelve are with more or less certainty referred to European 
Tertiary forms, chiefly Upper Miocene. One of the most 
characteristic and abundant of the new species, Cardium 
Tlartim.gi^ not known as fossil in Europe, is very common in 
Porto Santo and Baixo, and serves to connect the Miocene 
fauna of the Azores and the Madeiras. In some of the 
Azores, as well as in the Canary islands, the volcanic fires 
are not yet extinct, as the recorded eruptions of Lanzerote, 
Tenerifie, Palma, St. Michael’s, and others, attest. 
Lower Miocene Volcanic Rocks. —Isle of Midi and Antrim. 
—I may refer the reader to the account already given (p. 
247) of leaf-beds at Ardtun, in the Isle of Mull in the Heb¬ 
rides, which bear a relation to the associated volcanic rocks 
of Lower Miocene date analogous to that which the Madeira 
leaf bed, above described (p. 532), bears to the Pliocene lavas 
of that island. Mr. Geikie has shown that the volcanic rocks 
in Mull are above 3000 feet in thickness. There seems little 
doubt that the well-known columnar basalt of Staffa, as well 
as that of Antrim in Ireland, are of the same age, and not 
of higher antiquity, as once suspected. 
The Elf el. —A large portion of the volcanic rocks of the 
* Hartung, Die Azoren, I860; also Insel Gran Canaria, Madeira imd Por¬ 
to Santo, 1864, Leipsig. 
