SILURIAN, DEVONIAN, AND CARBONIFEROUS ROCKS NEAR LONDON. 289 
other Palaeozoic rocks ranging from the Belgian and north 
French areas towards or under the south-east of England. A 
spot at Archer’s Wood, Netherfield, near Battle,* was selected 
to determine this, by means of the diamond boring process, 
and no less than 1,998 feet were passed through, ending in the 
Oxford Clay at that depth. The Purbeck and Portland beds 
were but thinly represented in the boring ; but the Kimmeridge 
Clay, of unprecedented thickness, equalled nearly 900 feet, or 
three times its normal thickness ; this doubtless was owing to 
the depression of the Wealden area during the deposition of the 
Kimmeridge Clay, its accumulation being equal, pro rata , to 
subsidence. From top to bottom of this formation it was richly 
fossiliferous, every core yielding the characteristic Kimmeridge 
fossils. The Coral Rag was passed through, and the bottom of 
the boring-rod, with its diamond crown, was forced to yield 
to circumstances and end in the Oxford Clay. The first and 
only attempt to solve an important problem, purely for scientific 
purposes, was thus abandoned owing to the smallness of the core, 
and we still remain in ignorance and doubt as to the nature and 
depth of the older rocks in the south-east of England. The 
name of Willett will ever be honourably associated with this 
memorable undertaking, for at his suggestion and through 
his laborious efforts and labours, and under his guidance, it was 
commenced and continued; the ending and stoppage being 
due to want of machine power to penetrate deeper, and the 
too rapid decrease in the diameter of the cores. Subsequent 
boring, however, in search of water in the heart of London, at 
1,140 feet revealed the Upper Devonian rocks, thus clearly show- 
ing that the expected and sough t-for Palaeozoic rocks should be, 
and doubtless are, under the Wealden area, but whether Coal 
Measures, Carboniferous Limestone, Devonian or Silurian, we 
have yet to learn. In Calais the Coal Measures were touched at 
1,032 feet; Kentish Town, red rocks below the Gault at 1,114 
feet; Devonian, in Tottenham Court Road, at 1,140 feet; at 
Crossness, red sandstone at 1,056 feet; thus showing that a 
broadly spread floor of Palseozoic or most ancient rocks is spread 
under the extensive region of the south-east of England. 
To show still more conclusively the extension and easterly 
spread of the older rocks from the westward, we cannot pass 
over the important boring at Bradwell, near Burford, in Oxford- 
shire, where at the depth of 1,184 feet the Coal Measures were 
determined, several species of characteristic coal plants being 
brought up in the cores. Whether we are to look for a southern 
prolongation of the Warwickshire or South Staffordshire coal- 
field, or whether it is the setting in of another extensive coal- 
* Vide pi. vii. sections 1 and 3. 
NEW SERIES, VOL. III., NO. XI. T T 
