Farminr/ of Monmouthshire. 
279 
At or near Blackwood the lowest seam of coal would probably 
be found at the ijreatest depth from the surface, as the upper seam, 
which is known as the Mynyddyslvvjn seam, and which has fre- 
quently been worked by levels from the mountain sides, is here 
worked by means of a deep pit, having been displaced or thrown 
down by a fault. 
On this formation, which extends over such a large portion of 
the county, the sandstones and dark-coloured clays are in an un- 
improved state most unfavourable for agriculture. Indeed, it has 
been stated that the worst land in England lies upon the Coal- 
measures ; and certainly at its best it is but hungry soil. How- 
ever, by draining and liming, it can be rendered in a measure 
productive, except in the most elevated parts, where shales and 
sandstones occur at the outcrop. In some parts of the district 
the elements of a good soil are present, and Irequently each may 
be greatly improved by an admixture of the other. 
(c) New Red Sandstone. — This formation is of marked fertility, 
producing in rich abundance every kind of crop, and, where lime 
is at hand, great benefits result from its application. The neigh- 
bourhood of Crick, Portskewit, Magor, Chepstow, and Skenfrith, 
illustrate this. 
{b) Lias. — This is a cold wet tenacious clay, or a clayey loam 
on the limestone. When porous it is found to be adapted for cul- 
tivation, and grows good wheat and tares. At Lliswen and Maes- 
glaes, quarries have been opened, producing hydraulic lime, and 
yielding, from easily worked surface-beds, an abundance of cheap 
lime for the surrounding districts. 
(a) Alluvium. — Here we have a very great variety of soil, in 
appearance as well as in productiveness, arising partly from 
deficient drainage, partly from the character of the subsoil, and 
sometimes from the elevation. 
The washes on the alluvium are numerous, and some of them 
of considerable extent. The principal ones are Caldicot, Green- 
moor, Devandon, and Chepstow. 
The alluvium of the valleys of the Devonian area is wonderfully 
rich, and cheaply cultivated. Along the banks of the Usk it is 
of a faint red colour, and is as fertile as a garden. The alluvium 
of the hills, on the other hand, is of a thin peaty nature, with a 
sandy loam and clay, becoming marshy in the comparatively low 
grounds in the neighbourhood. 
Distribution of Rocks and Soils. — That portion of Monmouth- 
shire which lies east of a line drawn from Abergavenny to New- 
port, and prolonged thence to the Channel, is Devonian (ff 
on the Table of Acreage) Conglomerates, Sandstones, and Marls, 
except from Chepstow and Magor, where there is an oblong 
tract, parallel to the Severn, of Carboniferous Limestone (f), 
