XX 
PROCEEDIN'GS OF THE 
Field Meeting, 12th May, 1888. 
CHANDLER’S CROSS, WATFORD. 
From Watford Station, the party, about forty in number, under 
the direction of Mr. Upheld Green, walked through Cassiobury 
Park and Whippendale Woods to Chandler’s Cross. Then taking 
the private road leading to Micklefield, in a wood by the roadside 
half a mile beyond Chandler’s Cross, was seen the swallow-hole 
and chalk-pit which it was the chief object of this meeting to 
examine. 
The depth of the subsidence or erosion of the chalk in this dell 
was found to be from ten to fifteen feet, and the flints, occurring 
abundantly both in the superincumbent soil and in the chalk itself, 
were observed to present, without exception, evidence of erosive 
infiltration, resulting in geodes, some of which presented a handed 
structure, consisting of flint, chalcedony, and quartz crystals. 
Referring to these flints, the Director stated that they illustrated 
one of Nature’s battle-fields in which the two “ great powers,” 
silica or silicic acid and carbonic acid, had contended for mastery. 
The object of their ceaseless and never-ending strife was the posses¬ 
sion of the various bases, such as lime, potash, soda, and magnesia ; 
and the possessions of each appeared to be constantly exposed to 
attack by its opponent. In the depths of the earth-crust silica 
appeared to reign supreme, while at or near the surface carbonic 
acid successfully disputed its sway. The only base which silica 
succeeded under all circumstances in retaining was alumina, the 
silicate of which appeared to be as unaffected by carbonic acid as 
silica itself. This was well observed in the decomposition of 
felspars. Exhibiting various flints taken from the Chalk, Mr. 
Green showed how in some cases they were concretionary, and in 
others pseudo-morphic after organic remains, but that in all cases 
a subsequent alteration had taken place. In some cases this was 
probably owing to the decomposition of the silicate of lime by the 
constant percolation of water charged with carbonic acid dissolving 
out the lime, freeing the associated silica, and leaving it in the 
form of a siliceous meal, while in others the colloid silica had been 
dissolved out, allowing a re-arrangement of the crystalline particles 
in the form of chalcedony and quartz crystals. In some specimens 
the intermediate stages could be well observed. The late Dr. 
Mohr, of Bonn, had admirably compared the relationship of colloid 
to crystalline silica with that of barley-sugar to sugar-candy, the 
former in each case being readily soluble, the latter with greater 
difficulty, while the intermediate micro-crystalline forms of silica 
presented by flint, chalcedony, etc., would find their analogues in 
the more or less easily-soluble forms of so-called moist sugar. 
This Chalk dell, and the small wood or spinney in which it is 
situated, were then searched by the botanists of the party, and the 
columbine (Aquilegia vulgaris), coralwort (.Dentaria bulbifera), and 
spurge-laurel (Daphne Laureola) were found. The following mosses, 
also, were collected and identified by Mr. A. E. Gibbs :— 
