Inverted Mass of Upper Cretaceous Strata. 9' 



2. The Section. 



The only section showing all the above relationships at the present 

 time is that exposed in the sand-pit of Mr. Gregory Harris (No. 5)/ 

 to whose kindness we are indebted for permission to collect at that 

 locality. The main features of this striking exposm^e have been 

 described by Mr. Lamplugh, whose account of the strata may be 

 summarized as follows, from his descrijDtion of the succession seen 

 at the northern end of the pit (op. cit., Fig. 3, p. 238). 



In descending order, below 1 foot of soil : — 



A. Bluish-grey Boulder-clay ...... 2-6 feet. 



B. Gault : bluish-grey shaly clay above, dark-blue below . 4-7 feet. 



C. Irregular band of iron-grit ...... 1-3 inches. 



D. Ochreous or greenish-yellow loamy sand, grit, and 



breccia ; replaced here and there by lenticles of pale 

 flesh-coloured or yellowish gritty limestone, full of fossils 

 [the brachiopod-bed] ....... 1-2 feet. 



E. Undulating iron-grit band ...... 2-3 inches. 



F. Greyish loamy greensand, with clayey streaks and lenticles 



of pebbly grit ........ 2-3 feet. 



G. Lenticles of dark-red and ochreous iron-grit, with small 



included nodules of sandy pyritous claystone ; streaks 

 of fuller's earth, dark clayey greensand, and ochreous 

 loam below ; forming a well-defined band capping the 

 " silver-sands " . . . . . . . . l-lj feet. 



H. " Silver-sands," strongly cross-bedded .... 10-15 ft. seen. 



Mr. Lamplugh gave a full account of the lithological characters 

 of beds D and H, which, with the intervening strata, he ascribed 

 to the Lower Greensand. He also dealt at some length with the 

 bands, described by him as " iron-grit ", C and E. The section as 

 exposed in October, 1918, was substantially the same as in 1903, 

 though during the working back of the pit into the slope of the hill 

 the thickness of the Gault had increased to about 10 feet. The 

 Boulder-clay on the other hand had become reduced in thickness. 

 Early in 1919 an extensive mass of Gault Clay slipped down into 

 the pit and obliterated the whole exposure ; but during the past 

 summer the work of re-excavation has proceeded rapidly, so that 

 the section can again be studied at the southern end of the pit. 

 A result of the slip was to render the Gault accessible for examination 

 up to about 18 feet from its base, where it now shows a capping of 

 Drift so inconsiderable as to be scarcely distinguishable from the soil. 



A first glance at the section shows an apparent continuity within 

 the series of beds situated above the "' silver-sands " and below the 

 Drift. These strata are separated from the cross-bedded sands 

 below by a well-marked plane of division, having the appearance 

 of an unconformity. Mr. Lamplugh drew attention to this line of 

 demarcation, but ascribed ibo it a minor importance. He wrote : 

 " This line of junction seems to form a definite floor and to imply 

 some degree of erosion and unconformity. Yet in a mass so 



^ The numbers thus quoted in parentheses are the reference numbers showing 

 the position of localities on the sketch-map. Fig. 1. 



