DKIFT IN THE VALLEY OF THE CAM, ESSEX. 337 



find that, after boriug to the depth of 218 feet, the Chalk was not 

 reached, the whole being in Drift. I^ow, as in the next well to the 

 west, only 60 yards off, and at a slightly higher level. Chalk was 

 touched at the depth of 6 feet, it follows that there must he a fall 

 of the underground Chalk-surface of more than 212 feet in a 

 distance of 180, or about a slope of 1*2 in 1 (adding only 4 feet to 

 the 212). 



As the last well was only carried 6 feet into the Chalk, it may be 

 thought that this might be merely a boulder ; but it should be 

 noted that its evidence to the presence of Chalk in place is supported 

 by the other wells. Thus the one where the road to Eoyston 

 branches off, and which is only 125 yards from the deep Drift 

 boring, reaches the Chalk in 3 feet, and is carried 121 feet into 

 that rock. Again, the most northerly well, which is probably at 

 much the same level as the deep boring, reaches the Chalk in 6 feet, 

 and has been carried 19 feet into it, and this shows a fall of the 

 Chalk-surface of more than 212 feet in 270. 



Turning to the other side of the valley, we find that the Chalk 

 rises up from beneath the Alluvium, and is bare of Drift until 

 reaching the higher ground, from which it follows that the under- 

 ground Chalk-surface must again rise abruptly eastward. A section, 

 therefore, through Littlebury from east to^west would be as in 

 fig. 2, presuming that the Chalk would soon be met with by 



Pig. 2. — Section across Litilehury, from a little 8, of W. to a little 

 N. of E. (Scale 6 inches to a mile, or 880 feet to an inch *.) 



Village. 



1. Alluvium (and Kiver Gravel). 



2. Eiver Gravel. 



3. Glacial Drift. 



4. Chalk. 



* * Ordnance datum, 

 deepening the 218-feet boring, and giving the greatest possible lateral 

 extension to the channel of Drift : in other words, the slopes of the 

 underground Chalk-surface cannot be less than as shown, but may 

 be greater ; and it should be remarked that the vertical scale is not 

 exaggerated. 



* Ordnance Datum (mean sea-level). The thickness of 1 and of 2 exaggerated 

 slightly, of necessity. 



