1865.] WHITAKER ISLE OP THANET CHALK. 397 



of nodular flint, as its surfaces are very uneven, is a marked object 

 in the cliffs southwards from White Ness ; it is about three inches 

 thick, and at no great depth below the yellowish nodular bed of 

 chalk just noted. Other layers, though much thinner, seem to be 

 equally constant, occurring for miles along the coast. 



This more flinty and less jointed chalk forms the lower part of 

 the clifl^ all the way from Kingsgate to Ramsgate, but has for the 

 most part a capping of the higher or Margate Chalk, although some- 

 times the whole cliff from top to bottom is made of it, as at Broad- 

 stairs. 



Along this line of cliff, which is higher and rougher than that 

 where the Margate Chalk alone is present, the general aiTangement 

 of the beds is in the form of a very flat arch ; but there are a few 

 changes of dip, rarely at an angle of more than 3°, many smaU. 

 faults, and one fault of perhaps twenty or thirty feet downthrow 

 (south) at Dumpton Stairs. 



At Pegwell this division sinks below the level of the sea, and 

 westwards the Margate Chalk alone occurs, and is soon capped by 

 the Thanet Beds*. 



Very likely the Broadstairs Chalk will turn out to be the upper 

 part of the " Chalk with many flints " of the cliffs from Walmer 

 Castle to Dover Castlef, and which is there the highest division ; so 

 that the Isle of Thanet section would be the upward continuation of 

 that given by Mr. Phillips. 



Conclusion. — There are four remarkable points of Chalk geology 

 to be seen in the Isle of Thanet, the last two of which have not 

 been noticed in the foregoing remarks, to wit : — 



(a.) That the higher beds of the chalk contain a far less quantity 

 of flints than the lower. 



(h.) That they are the most affected by joints. 



(c) That large Ammotiites are found in them, which would lead to 

 the conclusion that the whole of the Chalk here belongs to the 

 Lower (or Middle) division of the formation ; and that therefore 

 there is no Upper Chalk in the eastern part of Kent, for the Mar- 

 gate Chalk is the highest in that district J. 



(d.) That the Tertiary beds seem to be here conformable to the 

 Chalk ; for just below the unworn green-coated flints that are always 

 present at the bottom of the Thanet Beds there is, in all sections in 

 the Isle of Thanet, a peculiar bed of tabular flint, the upper and 

 lower parts of which are of a whitey-brown colour and the middle 

 black. At Pegwell Bay there are a few inches of chalk between 

 this and the green-coated flints ; at some of the small outliers of 

 the Thanet Beds the two layers touch ; and near Chislet (west of the 

 island) the tabular flint is broken up and partly included in the bot- 



* I use the name "Thanet Beds" instead of ' Thanet Sands' (Prestwich), 

 because in these parts there is as much clay as sand in the formation. 



t W. Phillips, Trans. Greol. Soc. 1st ser. vol. v. p. 16; and Conybeare and 

 Phillips's ' Geology of England and Wales,' p. 90. 



X Mr. Prestwich has suggested that the highest Chalk under the Tertiary 

 beds of London belongs to the Middle rather than to the Upper part of the 

 formation. 'Water-bearing Strata around London' (1851), p. 331). 

 VOL. XXI. PAKT I. 2 E 



