Page:A Treatise on Geology, volume 1.djvu/73

Silurian System.^[1]

U p p e r S i l u r i a n.	$\left\{{\begin{matrix}\ \\\ \\\ \\\ \\\ \\\ \\\ \end{matrix}}\right.$	Ludlow rocks.
		Wenlock rocks.

660

$\left\{{\begin{matrix}\ \\\ \\\ \end{matrix}}\right.$

Upper Ludlow rock.

Laminated sandstone.

Aymestry limestone.

Subcrystalline limestone.

Lower Ludlow rock.

Sand shale, with concretionary limestone.

600

$\left\{{\begin{matrix}\ \ \\\ \end{matrix}}\right.$

Wenlock limestone.

Grey and blue subcrystalline limestonne.

Wenlock shale.

Shale and earthy limestone.

L o w e r S i l u r i a n.	$\left\{{\begin{matrix}\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \end{matrix}}\right.$	Wenlock rocks.
		Llandeilo rocks.

830

$\left\{{\begin{matrix}\ \\\ \\\ \end{matrix}}\right.$

Limestones and sandstones.

Laminated limestones and sandstones.

Conglomerates, &c.

Gritstones, conglomerates, limestones.

400

$\left\{{\begin{matrix}\ \\\ \\\ \end{matrix}}\right.$

Dark calacareous flags, sandstones, &c.

Cambrian System. (See page 124.)

Hypozoic Strata. (See page 111.)

Granite and other unstratified Rocks, the effect of Heat.

In possession of this complete section of all the principal masses of stratified rocks in the British isles, and guided by a map of the ranges of each of these on the surface,—aware, also, that within the narrow compass of these islands some of the groups of strata vary extremely (as the lower oolites, which are principally calcareous near Bath, but principally arenaceous near Whitby), and others have only a limited range (as the magnesian limestones), we may proceed to inquire how far the sections of other natural districts agree with that given above.

Throughout the great basins of Europe, and parts of Asia and Africa, including the countries bordering on the German Ocean, the Baltic, the Black Sea, and the Mediterranean, within the mountain boundaries of the Ural, Caucasus, Greece, Calabria, the Atlas, Western Spain, Brittany, Cornwall, the west of Ireland, Scotland, and Scandinavia, the general features and succession

1. As originally given by Murchison. (Sil. Syst. 1836.)