OTHER FORMATIONS DISPOSED IN BASINS. 527 
One highly beneficial result of the basin- 
shaped disposition of the Carboniferous strata 
has been, to bring them all to the surface around 
the circumference of each Basin, and to render 
them accessible, by sinking mines in almost 
every part of their respective areas ; (See PI. 65. 
Figs. 1, 2, 3.). An uninterrupted inclination in 
one direction only, would have soon plunged the 
lower strata to a depth inaccessible to man. 
The Basin of London, (PI. 67.) affords an ex- 
ample of a similar disposition of the Tertiary strata 
reposing on the Chalk. The Basins of Paris, 
Vienna, and of Bohemia, afford other examples 
of the same kind. (See PI. 1. Figs. 24—28.) 
The Secondary and Transition strata of the 
central and North Western districts of England, 
are marginal portions of the great geological Basin 
of Northern Europe ; and their continuations are 
found in the plains, and on the flanks of moun- 
tain regions on the Continent.* 
These general dispositions of all strata in the 
* The section (PI. 66. Fig. 1.) shews the manner in which the 
Strata of the Transition Series are continued downwards between 
the Coal formation and the older members of the Grauwacke 
formation, through a series of deposits, to which Mr. Murchison 
has recently assigned the name of the '' Silurian system." This 
Silurian system is represented by No. 11, in our Section, Fig. 1. 
The recent labours of Mr. Murchison in the border counties of 
England and Wales have ably filled up what has hitherto been a 
blank page, in the history of this portion of the vast and impor- 
tant Systems of Rocks, included under the Transition series ; and 
