358 Dr James Macaulay on the Fhijsical Geography^ 

 basalt ; the layer of lignite itself being covered by a thick ba- 

 saltic formation. 



The last and most important of the non-volcanic formations 

 is the limestone occurring near St Vincente. About two miles 

 up the valley, in a narrow branch ravine on the eastern side 

 of the river, and at an elevation of more than ICOO feet above 

 the sea, there is exposed by the mountain torrent a mass of 

 limestone surrounded on every side by the basaltic rocks. The 

 remains of one or two small kilns are near the spot. The small 

 extent of the formation that can be exposed, and the great 

 difficulty of transportation, must have led to the abandonment 

 of the working of the lime for building purposes. Mr Bow- 

 ditch' s account of " a bed of transition limestone seven hundred 

 feet tliick^'' and referred to by Dr Daubeny (in his book on 

 Volcanoes, p. 261.) and others, is altogether erroneous. The 

 account he gives is as follows : '* This limestone is crystalline 

 in its texture, contains very little siliceous matter, and scarcely 

 any compact masses ; yet, from the great depth of the bed (being 

 nearly 700 feet from its junction with the superincumbent ba- 

 salt, to my last glimpse of it in the bed of the torrent, nearly 

 level with the sea), without a single alternation, I have no 

 doubt of its being transitive rather than primitive limestone." 

 P. 51. With regard to the extent of this formation, I believe 

 that only a small portion of rock is exposed, and that quite 

 isolated by the igneous rocks which have raised it to so remark- 

 able an elevation. Mr Bowditch may have observed other 

 portions in situ 700 feet below the upper station ; but assu- 

 redly there is no bed of that thickness " without alternation." 

 In ascending the bed of the mountain stream, I observed large 

 masses that had been borne down from above, which may have 

 been the source of the mistake. If the limestone existed " in 

 the bed of the torrent nearly level with the sea," the lime- 

 kilns would not have been built at the upper limit of the for- 

 mation, where the difficulty of transportation has partly caused 

 them to be abandoned. Again, with regard to the structure 

 of the rock, it contains many fossils of the tertiary series. Mr 

 Smith obtained specimens of the following genera, Venus, Tel- 

 lina, Crassina, Astrea, Pecten, Cardiuni, Fasciolaria, Murex, 



