Vol. 58.] | PHYSICAL DEVELOPMENT OF BARBADOS, ETC. 365 
superficial coral-layers or pockets were probably formed upon the 
surfaces of what are now the raised White Limestones. It was 
during these mid-Pleistocene changes of level, carrying the island 
down to 1000 feet below the present altitude, and raising it again, 
that the waves cut out the sea-cliffs which now form the faces of 
terraces. Since their elevation small ravines have been formed, 
which dissect their edges. This late ravine-feature is mostly 
observable on the drowned coastal shelves of the northern islands, 
thus showing that the last movement of depression has not advanced 
so far in Barbados as it has in the north. 
The question of local elevation due to volcanic forces in other 
islands is not involved in the study of Barbados, but only that 
relating to great regional movements. All the late minor changes 
have not been fully studied. While much is yet to be learned 
concerning the Antillean chain, the problem of the changes of level 
of Barbados and Trinidad cannot be solved by the investigation of 
these islands alone, but it must be studied in connection with those 
of the other islands. While there are occasional references to other 
islands, a correlation of the phenomena described in the series of 
papers of which this is the last, and in the paper of Prof. Cleve on 
the Virgin Islands, should be made, pointing out the development 
and modification of features in different localities, where the record 
of the geological history of the West Indian region may be found. 
Discussion [ON THE TWO FOREGOING PAPERS]. 
Prof. Hut expressed his gratification at being the channel of 
communication of these papers to the Society ; though, as the Author 
was himself a Fellow, this was unnecessary. He understood that 
these papers completed the series in which Prof. Spencer had 
embodied the results of an elaborate survey of the great oscillations 
of level which the West Indian Islands had undergone in late 
Tertiary and post-Tertiary times, causing a connection, as he 
maintained, to be established between North and South America, 
and the formation of submerged valleys and embayments. 
Dr. Biranrorp agreed with Prof. Hull in his appreciation of the 
value and importance of the Author’s descriptions of West Indian 
geology. He especially called attention to the new light thrown 
on the Raised Coral-Reefs of Barbados, which, instead of being of 
one age, as they were described by Prof. Harrison & Mr. Jukes- 
Browne, are shown by both physical and paleontological characters 
to belong to two (or perhaps three) unconformable series of different 
ages. In one of the principal conclusions to which the Author had 
come—his view that the whole of the West Indian Islands formed a 
high plateau uniting North and South America in the Pleistocene 
Period—the speaker was unable to concur. The Author's principal 
evidence was derived from submarine troughs and valleys, which he 
regarded as proofs of subaérial erosion during a period of elevation, 
but the origin of these depressions is doubtful. On the European 
shores, the finest submarine valley known (the ‘ fosse du Cap Breton’) 
corresponds to no river, and there is no submarine trough of any 
