part 1] GATJLT AND LOWER GEEEXSAXD KEAR LEIGHTO]S". 29 



The following observations, compiled from a sketch-section in 

 my note-book, represent the present condition of the pit. 



Western side of Heath House pit; October 12tli, 1920. 

 Surface, at the highest part, 400 feet 0. D. 



In top breakaway ; — ■ 



ZY 



-—. Pale-grey weathered Gault clay : little or no drift 2 to 4 feet seen . 



4 



n s ' p e s : — 



5. Slips of pale-grey Gault : thickness, displaced, or not seen about 8 feet. 



Pale hard nodules weathered out, and hard fragments of 

 keeled ammonites: 'Ammonites rostratus,' 'Inoceramus 

 sulcatus,' 'Dentaliuni,' etc.: aho on the lower slope, 

 'Ammonites cf. splendens' : probably mostly from the upper 

 part of the section. 



Section at the northern end of the pit in a trench cut for 

 the Geological Survey; March 30th, 1920. 



All the beds may be slightly slipped here. 



Clay, with ' Inoceramus sulcatus ' (absent in beds below). 

 4. Darkish bine Gault, with 'Inoceramus concentricus' and allies: 



crushed imperfect ammonites : 'Eelemnites minimus ' : seen 4to5fcet. 



Exposed in a steep bank above a low crag of ironstone and 

 ferruginous Sand at the southern end of the pit. 



4. Dark greyish weathered Gault, with a few small smooth brown- 

 coated nodules : traces of pyrites : some ' race ' : may be 

 slightly displaced by slip 2 to 3 feet seen. 



3. Iron-grit breccia, poorly exposed; ochreous; with tabular pan 



1 to 2 inches thick and worn iron-grit fragments about 1| feet. 



1. Ferruginous coarse cross-bedded Sand ; indurated at the top 



into massive iron-grit, forming a flat-topped crag seen 5 to 6 f t et. 



Chamberlain Barn pit. — Rather over half a mile south of 

 the last-mentioned pit, an instructive section has been lately 

 exposed in the eastward extension of Chamberlain Barn pit, a big 

 working on the northern outskirts of Leighton Buzzard, which has 

 been gradually pushed back towards the western foot of Shenley 

 Hill, and is now in places within 1000 yards of the nearest 

 Shenley pit (see fig. 1, p. 2). All the western part of the pit was 

 entirely in sand, but indications that the base of the Gault was 

 not far distant on the east were observed in 1912, and the junction 

 is now visible in the working-face for over 200 yards, while a still 

 better section (fig. 16, p. 30) has been exposed in a cutting for a 

 light railway leading into the pit from the eastern side. The 

 section is of particular consequence, in proving the relation of 

 the iron-grit breccia and the associated fossiliferous limestone 

 of the Shenley sections with the fossiliferous beds of the zone 

 of Ammonites mammillatus, previously recognized in certain pits 

 south of Leio'hton. 



