185/.] PRESTWICH — BORING AT HARWICH. 251 



another inclined to the first at an angle of 30° ; and, allowing for 

 the smallness of the specimens and the difficulty of very exact deter- 

 minations, it seems probable that these two planes may possibly be, 

 the one a plane of dip of about 55° and the other a rough cleavage- 

 plane of about 84° to the horizon. Of the direction of the dip I 

 have no evidence. The overlying beds themselves here have a not 

 unimportant dip ; for in an old well in the vicinity the chalk is 

 64 feet deep, and in another 70 yards north, and on the same level, 

 it is 88 feet deep, showing that the chalk and tertiary strata here dip 

 about 9° southward, — a fact further corroborated by the circum- 

 stance that the chalk rises out at sea at the distance of a few miles 

 southward, off Walton. These facts render it almost certain that 

 this rock cannot belong either to the Cretaceous or the Oolitic series, 

 but probably belongs to some of the older slaty rocks. 



This Harwich well has an important bearing upon the character 

 of the evidence furnished by the Kentish Town well. The discovery 

 there, under the chalk, of greenish and red sandstones and clays 

 was so unexpected, that, although it was evident that they closely 

 resembled some parts of the New Red Sandstone (and, without evi- 

 dence to the contrary, such similarity of lithological character must 

 be accepted as the best proof that could be obtained), still the ques- 

 tion could not be considered as fully settled without some more 

 positive evidence, the more especially as M. Jus showed me some 

 fragments of cretaceous Ammonites and Belemnites brought up with 

 the red clays ; but, as I then observed, they might have fallen down 

 the side of the bore-hole from the cretaceous beds above. Some clay 

 which I had washed on purpose yielded no fossils*. 



Nothing further has been done to the Kentish Town well ; but the 

 evidence which we have now obtained from the boring at Harwich, 

 combined with that of the Calais boring, is corroborative, and of 

 such weight, that I do not hesitate to modify materially my former 

 opinion of the continuous range of the Lower Greensand under 

 London, and to adopt in great part Mr. Godwin-Austen's very in- 

 genious and philosophical hypothesis of the extension of an under- 

 ground tract of the older rocks, ranging from the mountains of the 

 Ardennes in Belgium to the Mendip Hills in the West of England. 

 Before the result of the Kentish Town well was known, Mr. God- 

 win-Austen had arrived at the conclusion that a tract of old rocks 

 underlies the Wealden ; but he probably was as little prepared 

 as I was for so remarkable a confirmation of his hypothesis as that 

 furnished by the well at Kentish Town, as there, not only were all the 

 Oolitic series wanting, but the Lower Greensand itself was absent. I 

 fear, therefore, that there is, under the central part, at all events, of 

 the London Tertiary area, a tract or ridge of the older rocks imme- 

 diately underlying the Chalk and Gault, on different portions of which 

 the three wells of Calais, London, and Harwich have touched, the one 

 on the Carboniferous series, the other on the New Red Sandstone, 

 and the last on some slate-rock to which, in the absence of organic 

 remains, it is not yet possible to assign its exact position in the palse- 

 * Quart. Journ. Geol. Soc. vol. xii. p. 10. 



VOL. XIV. PART I. S 



