Geology, and Climate of the Island of Madeira. 361 



the present geological epoch, these seas have been the site of 

 subterranean and submarine volcanic action on the vastest 

 scale. Since the year 1445, when the Portuguese navigators 

 found a new island of great size raised above the sea, till our 

 own times, as in the instance of the island of Sabrina, which 

 was more than three hundred feet above the sea and a quarter 

 of a league in circumference, many similar occurrences have 

 been recorded, proving the extent and power of the igneous 

 agency, yet* operating in this district of the eastern Atlantic. 



In regard to the geological age and history of the island, 

 the fossils are not yet sufficiently known to admit of great pre- 

 cision of statement. From the fossils of the limestone of St 

 Vincente, the oldest formation that has been observed, it ap- 

 pears that the island was first raised from the sea during the 

 tertiary epoch. 



The volcanic fires must have remained in activity, with in- 

 tervals at least of repose, during a long series of ages, because 

 the different formations indicate many eruptions distinct in 

 their character. Much of the island seems to belong to the 

 very latest or Pleistocene ages of the tertiary epoch. 



It seems further probable, that the conglomerates, of which 

 the great mass of the island is composed, as well as much of 

 the compact basalt, were formed beneath the ocean, and raised 

 by the force of elastic vapours and the upheaving of successive 

 volcanic products ; the island being chiefly the product of sub- 

 marine volcanic action. The beds of scoriae and light lapilli, 

 and the series of basaltic formations subsequent to them, shew 

 that the island was for a long period also a subaerial volcano. 

 It is farther apparent from those pumice beds (originally de- 

 posited horizontally above the sea level, but afterwards dis- 

 turbed, and now dipping down at considerable angles under 



* Last winter, on the 5th of December, the whole of the south coast of 

 St Miguel, one of the Azores, was inundated by the sea, which suddenly 

 rose upon the land with prodigious force, destroying many houses, bridges, 

 and other buildings, and causing great havoc and loss of property. We 

 heard of the disaster soon after in Madeira, but no trace of the submarine 

 disturbance was obser\'ed there. 



