256 



surface. Most of the alluvial tracts in this part of the colony (Liver- 

 pool Plains, &c.) are spoken of as consisting of rich, black, loose mould, 

 formed by depositions from the hills, which on the slopes arrays itself 

 into ridges, and in the plains into alternate hillocks and cavities. 



Much red sandstone with salt springs is stated to exist in the inte- 

 rior, as well as on the coast of the colony, and the red, loose, sandy 

 soil is said to be generally covered with the " iron tree", and with 

 long, weak spikes of flaccid grass. It is to the want of an admixture 

 of clay, or any retentive stratum, with the sands, that the author attri- 

 butes the great deficiency of water in the colony, boring having been 

 found quite useless throughout the absorbent sandstone country, al- 

 though in the immediate flanks of the primary ridges water gushes 

 out freely, and chalybeate and saline springs occur at short distances 

 from each other. 



The coal of the colony appears to be a lignite, and is associated 

 with grey marlstone containing impressions of leaves of dicotyledonous 

 plants. The secondary rocks contain casts of Terebratulse and other 

 shells j but the author does not attempt to make out precisely the 

 order of superposition, or the equivalents of the strata. 



A memoir was then read "On the Geology of the Island of Juan 

 Fernandez, in the Pacific Ocean, by Alex. Caldcleugh, Esq. F.G.S." 



After a sketch of the past history and present state of this island, 

 celebrated as the place of exile of Alexander Selkirk, the author pro- 

 ceeds to state that it is about twelve miles in length and four in 

 breadth, possessing three ports, and consisting of very high land, the 

 culminating point of which rises to about 3005 feet above the sea. 



The author could discover no trace of a volcano said to exist here 

 by former visitors 5 all the rocks, according to him, consist of basaltic 

 greenstone and trap of various mineralogical structure, both amorphous 

 and vesicular, together withtrappean concretions, no other contained 

 minerals being observable except olivine and chaux cctrbonatee metas- 

 tatique. It is further mentioned that the basalt in parts is almost 

 columnar, and in others has a peaked and serrated outline, the mass 

 being, here and there, traversed by dykes. 



Owing to the peculiar character of this basalt, and especially from 

 the great quantity of olivine, the author compares its age with that of 

 the basalt of Bohemia, the Rhine, the Vivarrais, and Beaulieu in 

 Provence. 



After the ordinary business of the evening had been concluded, a 

 Special General Meeting was held, when it was unanimously resolved, 

 that the Session should terminate, for the future, on the first evening 

 of Meeting in June. 



