596 PROCEEDINGS OF THE ACADEMY OF [NoV.^ 



inland there is a salt pond, while still further inland the cane cul- 

 tivation covers all exposures. At Corbizon Point, however, the upper 

 flinty layers carry fragments of silicified wood, and this is the horizon 

 of the silicified wood for which Antigua is noted. This horizon may 

 be traced across the island by the silicified wood and to some distance 

 to the southeast by the flint and chert with the fresh-water fossils. 

 Mr. W. R. Forrest informs me that the silicified wood is in place 

 along the north shore of Willoughby Bay; but, if so, it is not this 

 layer, always supposing that the map of Purves is correct. The 

 fresh-water fossils have not been determined specifically, a list of 

 the genera found is given by Purves. Collections of them which I 

 obtained at Dry Hill are now being studied and will be reported 

 upon later. 



The silicified wood, for which the island is noted, probably all 

 comes from this horizon. It is found throughout the Central Plain, 

 especially in the central part of the island, and lies about on the 

 surface in fragments of varying sizes, although nowhere, at present, 

 are trunks of 14 feet long by one foot or more in diameter encoun- 

 tered, such as are described by Dr. Nugent. These silicified woods 

 are found scattered about upon the surface, but are rarely seen 

 in situ; they are very plentiful at Bellevue and at Cassada Garden. 

 They include both Monocotyledons and Dicotyledons, but have 

 never been studied specifically. Purves mentions having found 

 stems and fruit of Chara 'in the beds carrying these deposits. The 

 shales at Dry Hill which overlie the fresh-water, mollusk-l^earing 

 flinty layers carry fragments of leaves of palms and other vegetable 

 matter; these beds are mixtures of kaolin and volcanic ash, and, 

 while brownish or dun-colored from the admixed vegetable matter, 

 they are evidently a part of the white shales and tuffs of the upper 

 layers of this division. As has been stated, these upper shales and 

 tuffs are well exposed at Scotts Hill, some two miles to the southeast 

 of St. John's, where they are quarried for road metal. They are 

 here hard and compact, breaking into angular fragments on exposure, 

 and wearing down, when used on the roads, to a tenacious clay. This 

 rock consists, as seen under the microscope, of kaolin mixed with 

 volcanic ash, the kaolin largely predominating. It is partly ce- 

 mented by secondary silica from the feldspar of the volcanic ash. 

 It becomes calcareous towards the top and passes upward into the 

 marls of the white limestone or Antigua formation. Indeed, when 

 it is hard and compact, this rock closely resembles the harder parts 

 of the marl, and the application of an acid is often necessary to 

 distinguish it from the true mark 



