810 Dr. FiTTON on the Strata below the Chalk. 



distinct indications of the Oxford oolite, between the Kimmeridge and Ox- 

 ford clays. 



The line of hills, nowhere probably exceeding 600 feet in height, which 

 stretches for about forty miles from the chalk range of Cambridgeshire to the 

 north-west coast of Norfolk, bounds the fen-country like the low shore of a 

 sea ; and a very slight change of level would again convert the fens into a 

 shallow estuary, by the waters of which these hills would be washed at their 

 base. At present, the face of the heights is covered with vegetation, so that 

 it is only in detached spots casually exposed, that the strata can be seen. 



Not having, myself, any good section of this part of the district, Mr. Rose 

 has been so good, at my request, as to prepare an enlarged copy of the 

 sketch annexed to his paper on West Norfolk, on the line from SwaflFham to 

 Lynn, (see PI. X. a. No. 25.) ; and I have inserted also a section and a 

 sketch of Hunstanton Cliff, (Plate X. a. No. 26 ; and X. b, fig. 12, a, b, and c,) 

 the only natural section that is visible upon the coast. 



Dejios'its above the Chalk. — The portion of the fens immediately adjacent to the chalk-hills in 

 West Norfolk, bears the name of Marshland. It is composed of alternating beds of lacustrine 

 silt and peat, covering, in the vicinity of Lynn, a deposit of marine silt ; the whole resting upon 

 a stiff clay, which incloses small nodules of chalk, and is obviously the same with the superficial 

 deposit, already described as including chalk fragments and being generally of similar com- 

 position, in Cambridgeshire and near Leighton ; beneath which are the strata of Kimmeridge in 

 Oxford clay. 



In a well, sunk and bored at Lynn, to the great depth of 630 feet, the detail of which will be 

 mentioned hereafter, a bed of the clay containing portions of chalk, was found beneath about 23 

 feet of sand, loam, and peat, and marine silt ; and the clay was, at the bottom, in immediate con- 

 tact with what Mr. Rose considers as the Oxford-clay, but with some doubt whether it may not 

 be that of Kimmeridge. For an account of the newer subaqueous deposits, and of the more 

 recent changes which the surface here is proved, by historical documents, to have undergone, I 

 refer to the publications of Mr. R. Taylor, Mr. Woodward, and Mr. Rose, in which references 

 will be found to preceding authors, some of whom are of very ancient date. 



Chalk,^— An account is given in the publications of this Society, of two borings in the south of 

 Norfolk, which illustrate the relations of the chalk to the beds immediately beneath it. One of 

 these, described by Sir H. Bunbury, was made at Mildenhall in Suffolk*, a spot about twenty miles 

 north-east of Cambridge, and thirteen from Ely, near the point where the chalk range changes 

 its direction from about south-west and north-east, and runs northward, to join the sea at Hun- 

 stanton f. Another sectional list has been published by Mr. John Taylor, derived from a boring at 



* Geol. Trans. 2nd Series, vol. i. p. 379. 



t The general course of the chalk escarpment in the Wolds of Lincolnshire (see a paper by 

 Mr. Bogg, Geol. Trans. 1st Series, vol. iii. p. 392.) and of Yorkshire, is from south-east to north- 

 west ; so that the line of its course in Norfolk may be considered as forming the bottom or most 

 eastern shore of a deep bay, (and the lowest part also of the range, with reference to the level of 

 the sea); from the extremities of which the escarpment diverges in both directions; — north- 

 westward, for about ninety miles, to its final termination on the parallel of Flamborough Head ; 

 and towards the south-west, for more than two hundred miles, to the coast of Devonshire. 



