12 F. L. KitcJiin and J. Pringle — 



replaced. But the purity of the limonite varies mucli, even within 

 the sandy strata. We do not consider that Mr. Lamphigh's term 

 " iron-gT'it ", as appHed to these bands, is quite happily chosen. 



Bed D, which contains the lenticles of brachiojood-limestone, is 

 of a complex character ; it may be more conveniently discussed 

 on a later page in the light of information obtained at other sections. 

 Its confused aspect is the result of a remarkable collocation of 

 heterochronous elements. While the lenticles of brachiopod- 

 limestone belong to the basal bed of the Chalk, there are other 

 lenticles of sandy clay, often with rounded grit-grains and pebbles, 

 which contain angular or subangular fragments and rounded 

 pebbles of ironstone ; these masses, together with some patches 

 and streaks of yellowish sandy and earthy-looking clay, are remnants 

 of the basal bed of the U23per Gault. The separate lenticles of diverse 

 origin and age are brought into juxtaposition in such a manner as 

 to appear as if they had originally occupied the same general plane 

 below the base of the Gault Clay in this section ; and they have 

 acquired a certain spurious resemblance to one another as a result 

 of secondary ferruginous staining. 



Other 23oints must be noted here, the significance of which will 

 appear in our further discussion of this composite bed. In the 

 lenticles and streaks belonging to the base of the Upper Gault we 

 have seen occasional small white calcareous nodules. In one of these 

 irregular streaks we found a flat pale-brown claystone nodule, the 

 source of which, in a stratum of pre-interruptus age, can be traced 

 in another section. The lowest two or three inches of the Gault 

 Clay, in contact with the limonite-sheet overlying bed D, are in some 

 parts shaly and fissile in the horizontal direction, and are stained 

 to a reddish hue. 



3. The New Evidence. 



Neighbouring exposures, where the lenticles of brachiopod- 

 limestone are absent, reveal varying stratigraphical relationships 

 which have an important bearing on the interpretation of the section 

 at Harris's Pit. The Gault Clay in these other sections, when 

 present, is not the same Gault, either lithologically or palseonto- 

 logically, as that forming the 18 ft. mass above the brachiopod- 

 bed in Harris's Pit. Indeed, the clay and the brachiopod-limestone 

 of bed D in that section are quite local and narrowly circumscribed 

 in their occurrence, a point which we shall presently emphasize. 

 We soon recognized that an important break in the succession 

 occurs there below the brachiopod-limestone. 



The fossiliferous limestone-lenticles, which had already received 

 so much attention, seemed to speak for themselves and to require 

 no further palaeontological study ; hence it appeared advisable in 

 the first place to examine the credentials of the supposed Lower 

 Gault above. Fossils were collected from it at successive levels, 

 and a comparison was made with the Gault seen in normal position 



