12 
THE GEOLOGIST. 
Add to all these natiu'al advantages a very large supply of coal im- 
portant for G ovemment use, some very intelligent masters and over- 
seers, cheap labour, and easy access along the valleys* to the ports, 
and you vdW not wonder that South Wales should be prosperous. 
There is an Institute for Engineers specially for this coal-field ; and 
he must be a second-rate man who cannot realize his £800 or £1,000 
a-year at least by the charge of a set of works. Many of the owners 
are extremely wealthy, and hospitable too. And somewhere on the 
northern crop I ^asited a friend, who is at once magistrate of his dis- 
trict, lieutenant of a rifle corps, surgeon of a large work, organist, 
lecturer, a good geologist, and a kind man. 
The north and south borders are called respectively the north and 
south crops. Along the northern edge the strata lie pretty flat, or 
gently inclined. They rest upon the terrace of Millstone Grit and 
the Mountain Limestone precipices overhanging the red sandstone 
country of Crickhowel and Abergavenny. 
On the southern crop the beds of rock lie at a steep angle, and 
again fi'om beneath them come out the Millstone Grit and Moumtain 
Limestone of Ox^^dch and the Mumbles ; or, further west, the gi'eat 
limestone clifis of Tenby, which of all places is the place to study 
Mountain Limestone, Old Red Sandstone, and contorted coal-strata. 
There is one more coal-field in Britain, but a poor one, the culm- 
measures of Devon, only worked for local use ; and it is more than 
probable that these culms are coal-beds in the Millstone Grit series. 
For in Scotland, of which we have not yet said anything, and 
where the richest seams are found, not only in their proper beds, 
above the Millstone Grit, but in it and all through it. Nay, it does 
not stop here, for in the Lothians and Fifeshire, as indeed is the case 
in Northumberland, there are coals and coal-shale among the beds of 
Mountain Limestone, thin layers of this black fael lying under 
mountain masses of the limestone rock ; and here and there are coal 
sandstones, rippled and worm-marked, showing the action of large 
lakes, or, much more probably, of the tides on the surface only just 
before occupied by a coal forest. 
Nor is this all, for deeper still, and far below the Mountain Lime- 
stone, the Scotch coal-beds lie in the Lower Carboniferous strata. The 
celebrated Burdie House beds of coal and hmestone are among these. 
The great quaiTies of coal sandstone around Edinburgh, from 
which their fine building stones have been quarried, lie far below the 
lowest level of the Mountain Limestone. There is a charming little 
work — the " Story of a Boulder," told by Archibald Geikie, that gives 
a clear notion of the Scottish coal-fields in most pleasant and readable 
style. 
And then for Ireland. We might almost wite a chapter on the 
coal of Ireland as short as Swammerdam's famous chapter " On the 
Rats of Afi'ica" — " There are no rats in Afi-ica," said the naturalist ; 
and it is all but the same in Ireland. True, there is a patch or two 
* The Crunilin Viaduct in Taff Vale is a splendid work of ait. 
