Dr. FiTTON on the Strata below the Chalk. 309 



Traces of the Wealden in Northamptonshire. — The preceding statement is rendered more in- 

 teresting by the discovery at Wansford in Northamptonshire, a place about ten miles east of 

 Ridlington, and thirty from the chalk-hills in Cambridgeshire, of a mass of calcareous grit, 

 containing an impression of Lonchopteris Mantellii*, a fossil species found by Mr. Mantell in the 

 grit of Tilgate Forest, Sussex, and hitherto peculiar to the Wealden strata ; indicating therefore 

 the presence of that group at the distance of more than forty miles from the nearest point on the 

 south, at which its existence has yet been ascertained in England. For an opportunity of 

 examining the specimen in question, I am indebted to the kindness of Mr. Woodward of Norwich, 

 to whom it belongs ; and I find it to consist of crystalline calciferous grit, of a yellowish grey or 

 drab colour, containing a very large proportion of carbonate of lime, — which may very well have 

 formed a part of one of the concretions of grit subordinate to the Hastings sands. The form of 

 leaf of the plant is beautifully impressed upon the stone, and very well represented in the 

 plate of the Fossil Flora : and tlie only question is, whether the locality has been correctly 

 stated, which Mr. Woodward has no reason to doubt. It may be added, that the existence of 

 the Wealden in this new situation is rendered more probable by the occurrence of chalk in Rut- 

 landshire, at a point not less remote from the great body of that formation in the South-east of 

 England. 



Norfolk j-. 



(160.) The strata below the chalk appear only on the west of this county^ 

 and the series is generally the same with that of Cambridge ; but the Upper 

 green-sand soon ceases to be conspicuous,, or disappears altogether ; and the 

 Gault is so much reduced in thickness, and changes its character so remark- 

 ably, that it is only by means of its fossils and by tracing its continuity with 

 the more usual form of the stratum, that its identity can be ascertained. The 

 ferruginous beds of the Lower green-sand are sufficiently distinct, but the 

 formation is much thinner than in the south-eastern counties. No traces of 

 the Wealden or Portland groups have yet been found, nor are there any 



* Lindley and Hutton's Fossil Flora, (1835) vol. iii. p. 372. Plate 171. 



t The publications on the geology of Norfolk, besides the general maps of Smith and Green- 

 ough, and the County map of the former, relate principally to the eastern portion of the county. 

 But since these pages have been at the press, an excellent account of West Norfolk, by Mr. 

 R. C. Rose, of Swaffham, has appeared in the London and Edinburgh Philosophical Magazine ', 

 to which I beg to refer the reader who wishes for detail. The preceding papers relating to this 

 part of the county, are Mr. R. C. Taylor's plate and description of Hunstanton Cliff, 1823-; a 

 paper by the same author, on the alluvial strata and the chalk of Norfolk and Suffolk^ ; and a list 

 of the fossils of Hunstanton, in Mr. Woodward's Geology of Norfolk*. Some occasional notes 

 connected with the west side of the county, may also be found in the tracts more immediately 

 relating to the beds above the chalk. 



> Vol. vi. and vii. 1835—1836. 



* Phil. Magazine, 1823, vol.lxi. p. 81 — S3; republished in a tract on the Geology of East 

 Norfolk, Svo, 1827. 



3 Geol. Trans. 2nd Series, vol. i. p. 374—378. 



* "An Outline of the Geology of Norfolk," Svo, 1833. 



