THE BUILDING OF AN ISLAND. 97 



From the above quotations it is evidcMit lluit the limestone rocks men- 

 tioned as so closely associated with the volcanoes have been put down at least 

 during the eruptions, if not earlier, yet the evidence of the embedded fossils 

 shows them to be "post-pliocene"; from which it may be inferred that the 

 West Indian volcanoes are quite young in the world's geological history, and 

 much younger than the formations which make up the east and west axis 'of 

 these islands. 



Questions of geological age must be left to the Palaeontologists, yet it may 

 be here pointed out that there must have been land along the north and south 

 axis long before the existence of the present volcanoes. Dr. J. W. Spencer, 

 who has of late paid a great deal of attention to the geology of the West 

 Indian Islands, has concluded that in the volcanic islands, as well as in Antisfua, 

 there is an ancient base of trap rock, which he speaks of as "pre-tertiary trap." 

 In Antigua it is between this trap, exposed along the southwest coast, and the 

 limestones of the northeast that the strata containing silicificd fresh water shells 

 and silicified woods occur. The wood fossils prove that there must have been 

 land there at the time they were deposited, and it was this land which after- 

 wards sank under the sea and received upon it the limestone beds of the north- 

 east. In Barbadoes also evidence is found of an ancient land. The geology 

 of that island was described by Sir Robert Schomburgh in his History of Bar- 

 badoes, published in 1848, and it has been more fully described a few years 

 ago by the well-known English geologist Jukes-Browne and Professor Harrison. 

 The larger part of the island is covered with a coral formation, all of which 

 the latter writers consider to be very recent. Dr. J. W. Spencer believes, how- 

 ever, that there are remains of an older limestone formation than the recent 

 coral rocks. However this may be, the whole mass of limestones rests on an 

 older formation, which has been reached bv borings through the limestone in 

 several places, and which appears on the surface over a considerable area on 

 the east coast, an area which has been so variously carved out bv the streams 

 into hill and dale that it is locally known as Scotland. The " Scotland forma- 

 tion " consists mainly of a great thickness of sands and sandy elavs, some of 

 them hardened into stone, others having very little coherence. Sir Robert 

 Schomburgh calls attention to the shore sand in that district, pointing out that 

 it is quite unlike the sand on other parts of the coast, being siliceous while the 

 other is shelly; it is, in fact, the kind of sand which is mentioned in Part i of 

 this chapter as derived ultimately from granite. Over the " Scotland forma- 

 tion " is another coming between it and the coral limestone, and known as the 

 " Oceanic formation." Mr. Jukes-Browne and Professor Harrison give a full 

 account of this remarkable formation, which is made up of over 300 feet of 

 deep-sea deposits, some of the layers being chalky and abounding in foraminif- 

 erous shells, others consisting of fine clays of varying colours and siliceous 

 earth, the latter, with a thickness of 130 feet, being almost entirely composed 

 of the microscopic flinty skeletons (whole and fragmentary) of creatures 

 known as Radiolaria, and hence called Radiolarian earth, or, on account of its 



