SALTER — A CHRISTMAS LECTURE ON COAL. 
9 
remainder is hid beneatii the sea. But even that half will show the 
beds in the same order or succession. The Mountain Limestone is 
a fine rock, and forms most of the high moory ground on the west. 
Many a border skirmish has been fought upon the heather that 
Fig. 1.— Ideal Section of a Coal Basin, to show the usual arrangement of the Beds, and the 
Dislocations caused by Faults. 
a. Old Red Sandstone ; h. Carboniferous or Mountain Limestone ; c, Millstone Grit ; d. Fare- 
well Rock, sandstone chiefly; e, f, g, h, coal seams, or beds, the layers of coal fi-omone foot 
to ten feet thick, and with shafts piercing tM'o, three, or more of the beds, as the case may 
be ; i, Magnesian Limestone and Red Sandstone, unconformable on the Coal-beds. 
covers its surface ; and many a bold moss-trooper has ridden for dear 
life across the bogs that ornament this formation,* and the one suc- 
ceeding, viz., Millstone Grit. 
It should be noticed that the "Millstone Grit" is all or nearly all 
sandstone — sometimes clayey, but more often hard; and the lower 
part of the coal-formation itself is nearly all sandstone, with a few 
bands of clay or shale. But as we rise higher in the beds, the clay 
grows more and more, the sandstone still being present in large 
quantity, till shale, as it is called, often makes up the chief part of 
the beds. Under every seam of coal, with scarcely an exception, lies 
a bed of what is called fire-clay, a rather hard clay, which makes 
excellent linings for stoves and furnaces, and which besides is used 
for crucibles and other purposes. Of this clay more by-and-bye, 
when we come to speak of how coal is formed. 
c ^ c c c c c c 
Fig. 2.— Ideal Section showing Granite and KiUas (soft slate), with Metalliferous Veins. 
*, granite ; a, killas ; c, c, c, metal veins. 
And now it will be seen from our diagram, and from what has 
VOL. IV. 
* " He rode a small but hardy nag, 
That o'er a bog — from hag to hag — 
Could bound Like any Bilhope stag." 
B 
