230 Notices of Ilemoirs — Clement Reid — 



flint-gravel, partly of Glacial, partly of Palaeolithic age ; and one of 

 the greatest difficulties met with is the impossibility of deciding 

 whether any particular pit is in Glacial or in Post-Glacial gravel, 

 and whether the gravel passes under or over the Chalky Boulder-clay. 

 The material being used again and again, the composition of the 

 gravel is practically the same in each case, except for the occurrence 

 of implements in the newer one. 



The first thing to be done was to ascertain whether the Chalky 

 Boulder-clay, an undoubted glacial deposit, passes under or over 

 the PalEeolithic brickearth. "With this object, borings were made in 

 the pits out of which implements have been dug. The author 

 gives details of these borings, the results of which may be shortly 

 summarized thus : — In Eansom's (New) Brickyard, after penetrating 

 the Paleeolithic brickearth and underlying fluviatile loam to a depth 

 of 60 feet, some blue chalky clay was penetrated in Bore Hole 

 No. 2, and in BH 1 derivative fossils from the Boulder-clay were 

 obtained at about the same level in the lower part of the old 

 alluvium. In each case boring was stopped by gi'avelly sand full 

 of water. Other borings in Jeeves' Yard and in some old brick-pits 

 on Maydencrof't Farm yielded no trace of Boulder-clay. One only 

 (BH 12) passed through undoubted Boulder-clay. The section is — 



feet. 



{du"" 9 



ho^ed 6i 



Ancient | Yellow and -white marl and silt 2 



alluvium ( Yellow loam and small chalk pebbles \ 



Chalky Boulder-clay 9 



Loamy chalky gravel (base of the Boulder-clay) 2 



Gravelly sand (boring stopped by large stones) 8 



36 



The site of this boring is close to the western margin of the old 

 channel. Chalk appearing at the surface within a short distance. 

 The occurrence of the Chalky Boulder-clay at this spot at a high 

 level, and its absence, or representation by derivative material, at 

 lower levels in borings made nearer to the centre of the channel, 

 suggest that the channel was, to a large extent, excavated, or 

 re-excavated, after the deposition of the Boulder-clay, as was the 

 case at Hoxne. 



The course of the ancient silted-up channel cannot yet be defined. 

 Loam with Palaeolithic implements occupies a belt extending for 

 about a mile south of Hitchin. 



The imderlying river alluvium is entirely overlapped and hidden 

 by the Palteolithic brickearth, and is only to be seen where the 

 brickearth has been dug away. It is found in Eansom's and Jeeves' 

 brickyai'ds, and it has now been discovered half a mile to the 

 SSW., in two borings on Maydencroft Farm. It apparently 

 occupies a narrow belt in the middle of the old valley. Tlie 

 greatest depth of this valley could not be proved, owing to 

 the running sand and gravel, which made boring so difficult. The 

 bottom lies at least as low as the level of the existing valleys 



