HEETEOEDSHIEE XATUEAL HISTOEY SOCIETY. 
XXXV11 
Colne and passing through the "Watford tunnel, the line runs along 
the valley of the Gade as far as Two Waters, where the Gade re¬ 
ceives its tributary the Bulborne, half a mile from Boxmoor Station. 
Between this point and the station, but on the opposite or west 
side of the line, is the hill called Bough Down, in which a large 
chalk-pit is excavated. This has before been visited by the Society 
and also by the Geologists’ Association, but on this occasion for 
the first time the inspection of it was made by members of the two 
Societies in a joint field meeting, the directors being the Treasurer 
of the Geologists’ Association, Mr. Hopkinson, and the Secretary 
of the Hertfordshire Society, Dr. Morison. 
The interesting feature of the pit is the occurrence in it of the 
Chalk Bock, a bed of hard cream-coloured chalk, on which remarks 
were made by the Directors. As an account of this bed, by Dr. 
Morison, appears in the present volume of the ‘ Transactions ’ 
(p. 199), it need not be further alluded to here. 
After a few fossils had been found, the pit was left for the brick¬ 
fields at Bennet’s End, the route taken being by Two Waters and 
across the fields. These brick-fields are at a considerable height 
on the opposite side of the valley to Bough Down. They are on 
an outlier of the London Clay and Beading Beds, through which a 
fault runs nearly north and south, the Chalk abutting against the 
basement-bed of the London Clay. This is not clearly seen now, 
the beds not being worked in proximity to the fault; but the 
following section by Mr. Whitaker, reproduced from his ‘ Geology 
of London ’ (p. 209) by permission of the Director-General of the 
Geological Survey, shows what was to be seen in 1861. 
Diagram-section of a Pit near BenneVs Pnd. 
(a Roughly laminated brown clay, from 0 to about 6 feet. 
London | ( b Brown loam, over 6 feet \ 
Clay. ^ Basement- \ c Flint-pebbles and oyster-shells, about / About 
| bed. j 6 inches i 12 feet. 
(_ l d Brown loam, like b , 5$ feet / 
e Bluish-grey plastic clay of the Reading Beds, holding water. 
/ Chalk, abutting against the basement-bed of the London Clay. 
xx Line of clay along the fault. (The right hand part of the section, lightly 
engraved, not actually seen.) 
The basement-bed of the London Clay has here yielded many 
fossils, a list of which is given on pages 264 and 265 of Mr. 
