128 GEOLOGY. Tchap. VI. 



termed transition limestone, or one of the lowest of the 

 sedimentary formations of which the crust of the earth is 

 known to be composed. 



A gentleman, however, belonging to a more advanced 

 school of geology *, who has visited Madeira within a few 

 years, has shown that this supposition was erroneous, and 

 from the fossil shells, or rather casts of shells, which 

 he obtained in such a condition that he was enabled 

 to determine the genera, though not the species, to 

 which they belong, concluded the formation to be of the 

 Tertiary epoch. My father, to whom I owe the present 

 sketch of the geology of the island, discovered in the cal- 

 careous rock of S a .° Vincente numerous specimens of a very 

 remarkable species of Echinanthus, the E. alius of Gray, or 

 Clypeaster altus of Lamarck. This species is figured by 

 Scilla amongst the fossils of Malta. It is found in the 

 Miocene beds of that island, of Italy, and of Greece. De 

 Verneuil, in his notice of a geological map of Spain, says 

 that " in the Sierra Morena, near Cordova, are to be seen, in 

 a horizontal position in contact with the old rocks, the 

 Miocene beds with huge Clypeaster altus." f If we take this 

 fossil, then, as characteristic of the Miocene period, we have 

 a continuous line of tbat deposit established nearly east and 

 west from Greece to Madeira; and at the latter place its 

 formation has occurred in one of the intervals of a series 

 of basaltic eruptions and disturbances to which the island 

 owed its existence. 



The general correspondence of the shells and corals of this 

 bed in Madeira with that found at a lower level in the neigh- 



* Mr. Smith of Jardine Hill, see Geol. Trans., vol. iii. part ii. No. 73. 

 + British Association Report, 1S50. 



