688 ME. B. J. LECHMEEE GTJPtY ON THE GEOLOGY [KoV. I9II, 



fossil in the Eocene of Europe and living in America even as far 

 south as Venezuela. Again, there is Cyrena semistriata, a fossil 

 of the European Eocene also found fossil in late Tertiary beds in 

 Trinidad, and scarcely distinguishable from the living C. solida 

 of Central American rivers. Still these facts, although suggestive, 

 cannot be regarded as conclusive, for it is quite conceivable that 

 the freshwater chert might be (as it probably is) a later formation 

 than the rest of the Central Plain. AVe must, therefore, enquire 

 •what aid we can obtain elsewhere in determining the relative 

 ages of the formations of Antigua. 



In order that what follows may be more easily understood, I may 

 state briefly the conclusion at which I have arrived in reference 

 to this 'Central Plain.' The course of the great Antillean Disloca- 

 tion is shown in my paper already mentioned (Trans. Canad. Inst, 

 vol. viii, 1908-1909) by a curve extending from the Gulf of Cariaco 

 in Venezuela through the Gulf of Paria, and thence along the line 

 of the Antilles between St. Vincent, etc. and Barbados, and thence 

 northwards, turning to the west near the Virgin Islands. In the 

 north-eastern part of its course there are two points where the 

 dislocation shows itself above the sea-level, the remainder of this 

 part of its course being under water and inaccessible to observation 

 except by sounding. The two points referred to are Guadeloupe 

 and Antigua. This great fault, fissure, or dislocation divided the 

 island of Guadeloupe into two portions, the division between the two 

 portions being marked by a narrow channel called the Salt River. 

 Earther north it divided the Island of Antigua also into two portions, 

 the ' Central Plain ' of Antigua being situated upon the very fissure 

 itself, widened by the breaking-away of its edges and filled in by 

 the materials derived from the fracture and degradation of the 

 neighbouring rocks. It is not accurate to say that these islands 

 were divided by the dislocation ; they are really the product of the 

 dislocation : for, while on the western side of the fissure immense 

 volcanic activities were brought into play, producing the chain of 

 the Lesser Antilles, the sea-bottom on the eastern side was elevated 

 and even everted, bringing up above water in a few places the 

 Cretaceous and Tertiary deposits formed along the margin of the 

 Atlantis Continent, while the continent itself was sinking. In 

 the case of Barbados, an offshoot eastwards of the main dislocation 

 elevated that island, but produced no volcanic phenomena in its 

 neighbourhood. 



In the map appended to my Canadian Institute paper the 

 draughtsman omitted Antigua and the small islands in its neigh- 

 bourhood. The sketch-plan (PI. L) which I now present shows on 

 a larger scale than that map, and better than a verbal description 

 could show, the probable approximate line of dislocation. The 

 accompanying diagrams (fig. 2, p. 689), though not drawn to any 

 scale, give an accurate idea of the relations of the dislocation to the 

 surrounding formations. The first two of these diagrams (a) & (b) 

 are, of course, founded on actual observation ; but the third (c), 



