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have thinned away, as do most of the Secondary rocks, probably 
against the Palaeozoic plateau. 
The key to the underground Palaeozoic geology of the country 
south of the Thames, had it been completed , must have been 
the sub-Wealden boring. Unfortunately for science, the problem 
was never solved, the nearly 2,000 feet of Secondary strata 
passed through being all above the desired or anticipated ancient 
land. The fact that the Upper Devonian rocks were under the 
heart of London, and the Silurian some miles north of that, 
induces us to believe that we must look to the south of London, 
as pointed out by Mr. Gfodwin-Austen, as the area where 
we should expect to find the Coal Measures, ranging probably 
under or north of the North Downs. Their southern extension, 
until revealed through necessity or enterprise, will remain un- 
known, but we doubt not their presence. 
Palceontology of the Upper Silurian and Devonian Bocks 
north of London . 
The extensive area north of London occupied by the Tertiary 
strata as far as Ware, with the Chalk beneath, is now known to 
be underlain by other rocks of high antiquity, now determined 
to be, through organic remains, the Upper Silurian, and closely 
resembling, if not identical with, the Wenlock group of the 
Wren’s Nest, near Dudley, or even the more distant groups of 
the Wenlock Edge or the Ludlow Promontory. The facies of 
the fossil contents of the Upper Silurian cores at Ware is not 
that of the Malvern or Woolhope series, or of the still nearer 
beds at Tortworth, although nearly in the same latitude ; 
nor can they be correlated with the Upper Silurian series of 
the Ardennes in Belgium, from which they essentially differ. 
There can be no doubt of their affinity with the true Silurian 
rocks to the west of the Severn Valley, or the Dudley group, 
thus incontestably proving the easterly continuity and exten- 
sion of the latter. So rich in fossils are these Ware Silurians, 
that no less than thirty-three species have been obtained ; every 
portion teems with extinct life, especially Brachiopoda, twenty- 
one of the thirty-three species belonging to this group. The 
characteristic trilobite Phacops caudatus with Ischadites 
Kcenigii , Crinoidea, and Orthoceratites, are sufficient data in 
themselves to establish both the age and affinity of the fossils, 
which now are known to occur on this floor 800 feet deep, on 
which rest the Cretaceous and Tertiary series of Hertfordshire. 
The following list will show the rich fauna of the Wenlock 
Kocks below Ware. All the fossils were obtained from a core 
less than three feet in length and one foot in diameter. 
