402 Geological Society. 



12. " Report on the Existence of large Coal-fields in the Province 

 of St. Catherine's, Brazil." By Edward Thornton, Esq. 



The existence of Coal in this district has for many years been an 

 established fact ; but no practical exploration had been made until 

 the years 1861-63, when Viscount Barbacena, having purchased a 

 tract of land containing the best seams, ascertained the existence of 

 a series of coal-beds at nine different levels, underlying a sandstone 

 formation, horizontally disposed, and varying in thickness from 1^ 

 to 10 feet. Analyses of specimens of the coal prove it to be of good 

 quality, its profitable working depending solely upon the facilities for 

 transport. 



13. " On the Sources of the Materials composing the White 

 Clays of the Lower Tertiaries." By George Maw, Esq., F.L.S., 

 F.G.S. 



In examining some of the light- coloured deposits occurring be- 

 tween the Boulder-clay and the Carboniferous Limestone of North 

 Wales, the author was led to the conclusion that some of the beds 

 of very white and pure clays that occur in " pockets " in the lime- 

 stone could not have been derived from the mere mechanical degra- 

 dation of any previously existing materials ; analyses by Prof. Way 

 and Dr. Voelcker showed that they contained similar proportions of 

 silica and alumina as did the limestone, and Mr. Maw concluded 

 that they were left behind after the dissolution of the calcareous 

 matter of the limestone had been effected by carbonated water. 



The Lower Tertiary deposits of Hampshire, Dorsetshire, the Isle 

 of Wight, and Devonshire contain vast deposits of similar white 

 clays, which the author believed to have had an analogous origin 

 through a similar dissolution of the Chalk. 



14. " On the Postglacial Structure of the South-east of England." 

 By Searles V.Wood, Jun., Esq., F.G.S. 



This paper was an outline of the principal points deduced by the 

 author from his Geological survey of the country included in the 

 Ordnance sheets Nos. 1 & 2, where the glacial, clay approaches 

 nearest to the Thames Valley beds, and from a survey on a smaller 

 scale of the glacial beds over a much larger area. Both of his maps, 

 with a manuscript memoir upon the subject, have been placed by 

 him in the Library of the Society. 



The author took up the structure at the southerly and westerly 

 edges of the principal tracts of glacial beds, and in the parts where 

 these are divided by great troughs of denudation ; he showed the 

 manner in which the denudation, commencing at the first upheaval 

 of the glacial sea-bed, has descended through the Lower Tertiary 

 and Secondary deposits, accompanied by the formation of successive 

 gravel-beds during its progress. His conclusion was, that the re- 

 moval of the Lower Tertiary strata over much of the South of Eng- 

 land, and the excavation of the Weald Valley, as well as the great 

 denudation which the Liassic, Oolitic, and Cretaceous beds have under- 

 gone in the west of England, are to be traced principally to the pro- 



