126 



A. J. JUKES-BEOWXE OX THE 



§ 4. The Value of the Divisional Line between the Purjple 

 and Hessle Clays. 



I will now assume what appears to be the outcome of the pre- 

 ceding facts, namely, that some or all of the East Lincolnshire 

 Boulder-clay is newer than the Upper Boulder-clay of East Anglia. 

 "Whether all of it be of such newer date is still open to question ; 

 and this brings me to discuss the distinction which has been made 

 between the Purple and Hessle Clays. 



All the sections which, have come under my notice (showing the 

 junction of these two portions of the Boulder-clay series) I have 

 examined with a siDCcial view to this question ; and T may state at 

 the outset that I think Mr. Searles IVood has greatly exaggerated 

 the importance of this line of division. 



I make a few extracts from my notebook in support of this 

 opinion. 



At South-Eeston brickyard, 5 miles S.E. of Louth, an upper and 

 lower clay are clearly visible, the upper being reddish brown streaked 

 with grey, and including near its base a lenticular layer of brown 

 sand ; the lower is of a dark purple brown, without streaks : these 

 beds, however, are only separated by, two feet of brownish-purple 

 laminated loam, which rests evenly on the lower clay, and the whole 

 forms an unbroken succession. 



At Stewton brickyard, two miles east of Louth, the following 

 section was visible in 1882 : — 



feet. 



Loamy soil 2 



Eeddish brown clay, -with lenticular seams of loamy sand 



and silt 4 



YeUowish-bro-wii sand i-H 



Dark purplish-brown clay, seen for 6 



The sand-bed includes patches or layers of Boulder-clay, and 

 appears to be intimately connected with the clays above and below. 

 At one place it thickens to 2 feet,, and has a layer of small 

 pebbles at the base, but it is certainly not an important line of 

 division. The sides of the joint-planes and cracks in the upper clay 

 are ash-coloured, but those in the lower are in places stained with 

 dark greyish-blue, which would probably become ash-grey if exposed 

 more to atmospheric action ; moreover, the top of the lower clay 

 immediately underlying the sand is of the same reddish tint as the 

 upper clay. This seems to suggest that the colours of the upper 

 clay are due to alteration by surface agencies. 



Both here and at Eeston the upper clay is said to burn red in 

 bricks, while the lower clay burns white; can it be that there is 

 more oxide of iron in the former ? and is the purple colour of the 

 lower clay partly due to carbonate of iron ? 



The brickyard in James Street, Louth, shows : — 



feet. 

 Eeddish clay (grey-streaked), with a base of hard sandy 



and stony loam 14 



Purple -brown clay, with fewer stones 10 



