Reports and Proceedings. 127 



intervening between the Chalk and Boulder-clay of the high ground 

 of Suffolk. Many of the masses are several tons in weight. Although 

 they occur at a general level they do not form a connected band ; 

 loose Drift, out of which they were evidently composed, forming a 

 horizontal continuation of their strata. The drift is largely charged 

 with Chalk-detritus, which also occurs in the softer blocks ; some of 

 the blocks are extremely hard and compact, and in these the sandy 

 agglomeration seems to have given place to a crystalline structure ; 

 but the hardest of those found in situ were resolvable into sand by 

 the action of hydrochloric acid, and appeared to bo merely held to- 

 gether by a calcareous cement. 



A block resting on the Ked Crag near Woodbridge was found, on 

 analysis, to contain no lime, excepting a small quantity in the form 

 of silicate. 



The springs in the gravel-bed at Crowfield, near Coddenham, are 

 chalybeate, containing in solution Lime and Iron, which are precipi- 

 tated on standing, and much carbonic acid is evolved from a well 

 sunk through the gravel ; the author considered that the carbonic 

 acid may have been the solvent agentin forming the calcareous cement, 

 and that the first stage of the consolidation of the blocks of saccha- 

 roid sandstone may have been by the agency of calcareous matter ; 

 and he referred to the possibility of lime in solution, when in con- 

 tact with silica, giving rise to silicate of lime, a very small propor- 

 tion of which would form a powerful cement in agglutinating 

 siliceous particles together. 



2. " Notes on some Chemical Analysis of variegated Strata." By 

 George Maw, Esq., F.L.S., F.G.S. 



The author gave the results of some analyses for the determination 

 of Iron in the light and dark parts of variegated Slates, Sandstones, 

 and Marls, the colour of which is due to oxide of iron, and in which 

 the variegation appears to be disposed independently of mechanical 

 arrangement. The analysis in each case exhibited the fact that the 

 lighter blotches, spots, and stripes contained a smaller portion of the 

 colouring oxide than the average mass, a proportion which implies 

 an actual difference in the percentage of the metallic iron, and 

 which could not be accounted for by any mere difference in the state 

 of its combination. This shows an actual departure of a part of the 

 colouring oxide out of the colourless patches, and a dispersive pro- 

 cess which seemed to be the very reverse of the segregation of no- 

 dules of Carbonate of Lime and Carbonate of Iron out of a clayey 

 matrix. Among the forms of variegation referred to were : (1st) 

 that resulting from the segregation of dark blotches out of a lighter 

 matrix, the evenness of colour of which does not appear to have been 

 materially affected by the withdrawal of a part of its colouring- 

 matter ; (2nd) that resulting from the segregation of dark blotches 

 out of a lighter ground, each of which is concentrically surrounded 

 by a distinct and well-defined zone lighter than the general ground ; 

 (3rd) strata variegated with light blotches containing a smaller pro- 

 portion of colouring-matter than the general ground, but not ar- 

 ranged concentrically round a darker nucleus ; (1th) the variegation 



