190 Reports and Proceedings. 



evidence of the climate under -which they lived. He thought that where vegetable 

 structures were perfectly preserved in flint, the process of silicification had gone on but 

 slowly ; but this fell more within the province of the chemist than of the geologist. 



Mr. Hulke suggested the possibility of the fern having contained a certain amount 

 of silica while still living. 



Prof. Morris referred the fossil to the Thanet Sands. He thought that the silica 

 in fossil coniferous and endogenous wood varied in character, and this might throw 

 some light on the process of conversion. He considered that objects containing phos- 

 phate of lime, and those containing carbonate, were subject to different processes of 

 silicification. 



Mr. "Whitaker was strongly of opinion that the fossil had been derived from quite 

 the upper part of the Thanet Sands. 



Prof. Duncan called attention to the process of silicification as exhibited by the 

 Antiguan corals, in which one highly insoluble mineral had been replaced by another 

 almost as insoluble. 



Mr. Carruthers, in reply, did not think that anything eould be predicated as to 

 climate from extinct species ; if this were attempted, a similar error to that with 

 regard to the climate under which the fossil Elephants were supposed to have lived, 

 might be repeated. Existing Osmundacese contained no silica in their structure. 

 The peculiarity of the fossil under consideration was the preservation of the contents 

 of the cells, even to the starch which is so readily decomposed. The difficulty of 

 accounting for the replacement of soft vegetable matter by hard mineral silica, 

 seemed to him great. 



2. "On the Oolites of Northamptonsliire." By Samuel Sharp, 

 Esq., F.G.S. 



The author stated that his ultimate purpose was to describe seve- 

 rally the Oolitic beds occurring in the Northampton district, in the 

 more northerly parts of the county, and in the neighbourhood of 

 Stamford ; to exhibit fossils gathered from each locality, and to 

 correlate the several series, and thus to endeavour to establish the 

 character and sequence of the Oolites of this Midland district. He 

 anticipated, however, that the publication by the Geological Survey 

 of their maps and memoir of North Northamptonshire (the work of 

 Mr. Judd) would intervene, and might render superfluous the carry- 

 ing out this work in its entirety ; but in the meantime he submitted 

 his first part, " The Oolites of Northampton and Neighbourhood." 



The author stated that there were four areas within a compara- 

 tively small space in which the whole of the beds occurring in each, 

 from the Great Oolite down to the Upper Lias (inclusive), were 

 accessible. These were situated at or about : — 1, Kingsthorpe ; 

 2, Northampton ; 3, Duston ; 4, Blisworth. The Oolitic beds in 

 these several areas were described in detail, the beds of the North- 

 ampton Sand (as comparatively little known) being those to which 

 the greatest interest attached. These he proposed to class in three 

 divisions — the " Upper," the " Middle," and the " Lower" North- 

 ampton Sand. 



The individual beds of the several localities were shown to vary 

 considerably ; but collectively they would present the following 

 general section, the maximum thicknesses being given in feet : — 



Feet. 



f A. White Limestone, disposed in beds of from a few inches to about 

 H w I 3 feet in thickness, much fissured, and varying in character, and 



K g <^ containing characteristic Great Oolite fossils 25 



^5 5 I B. Blue and grey clay, dug for brick-making, with a ferruginous band 



l^ at base, and Great Oolite fossils 15 



