682 ME. E. J. LECHHEEE GUPPY ON THE GEOLOGY [Nov. I9II, 



always room for expansion and correction, and it is not possible 

 for any observer, however honest and painstaking, to cover without 

 error all the problems which present themselves, and to grasp 

 immediately the bearing of the features which come into view. 

 My short visit to Antigua revealed to me how ably the work 

 of Purves had been done, but my physical incapacities would 

 certainly have prevented me from adding anything of my own, had 

 it not been for the kindly aid of Mr. W. R. Forrest, a gentleman 

 whose amiable disposition, combined with his enthusiasm for the 

 study of nature, induced him to assist me. Therefore, it is to him 

 that I owe the possibility of presenting the following notes, which 

 are merely remarks on and deductions from the observations of 

 Purves and Spencer. 



Dr. Spencer's work is based on Purves's ; but, for convenience, I 

 refer here to Spencer's. His section ] across Antigua shows the 

 strata in the following order (omitting minor details) : — 



(1) Old igneous basement = South-Western Region. 



(2) Tuff series, with layers of marine cherty limestones 1 = Central 



and also freshwater cherty beds. j Plain. 



(3) White Limestone Series = Antigua Formation. 



An orderly and apparently conformable succession of these rocks 

 is here exhibited, each set underlying the next one in the order 

 stated, so that the White Limestone appears to overlie the Tuff 

 Series, which in its turn is superior to the igneous series. Purves 

 describes these rocks very fully, and Dr. Spencer gives a summary 

 of his description, remarking that there is nothing in the character 

 of the volcanic or igneous rock to establish its age, which must 

 (he says) be pre-Tertiary because it underlies Tertiary deposits. 

 My conclusions on this point will be gathered from what follows. 



It is admitted that the surface of Antigua is divided physically 

 into three regions, of which the boundaries run approximately from 

 north-west to south-east. Of these regions the south-western one is 

 igneous, while the north-eastern one is calcareous and sedimentary. 

 The middle portion between these two regions is a depression called 

 the ' Central Plain,' out of which rise several hills. It may be 

 broadly stated that the first-named or igneous region is a mass of 

 hills formed of volcanic craters and their ejectamenta, and that 

 they are for the most part covered by tuffs consisting of such 

 ejectamenta. All these are fully described by Purves and Spencer, 

 and the only observation that I would add on this point is that 

 I believe the ejectamenta to have been mostly subaerial and to have 

 been thrown out of the volcanic vents, forming layers which present 

 a stratified appearance, just as is the case with the similar deposits 

 of Mont Pele in Martinique and elsewhere. The effect of heated 

 gases and percolating water has been to consolidate these tuffs 

 more or less, and in varying degrees. 



1 Q. J. G. S. vol. lvii (1901) p. 492. 



