AGRICULTURAL CHARACTERS OF THE UPPER SILURIAN ROCKS. 253 



There is a peculiarity in the soil of the Upper Ludlow rock which might surprise a land 

 surveyor unacquainted with the geological structure of the district ; namely, its dryness, 

 or rather the rapidity with which rain is absorbed, a peculiarity seldom if ever observable 

 in soils containing so much clay. I attribute this property to the strata lying near the 

 surface, and being singularly full of joints and fissures 1 . The water having once passed 

 through the thin covering of earth, is rapidly carried off by these deep natural drains ; 

 the sloping position of the strata tending also to rapid desiccation. 



On the other hand the lower members of the Ludlow and Wenlock formations being 

 soft and argillaceous, and subject to the drainage waters of the upper, are comparatively 

 cold and unmanageable tracts. Yet even this remark is subject to wide exceptions, for 

 in all those situations where the limestones of Aymestry or Wenlock appear at the 

 surface and afford by their disintegration a certain quantity of calcareous matter, its 

 intermixture with the stiff clays forms a soil which yields excellent crops of wheat. 



The agricultural character of the Lower Silurian rocks differs much from that of the 

 overlying formations. In this region, where the best types are displayed, the distinction 

 is strongly marked as the observer passes from the valleys of clay or decomposed mud- 

 stone to the sloping ridges of Caradoc sandstone. These rocks, being for the most part 

 arenaceous, disintegrate to a sharp soil, not usually very productive, though in those 

 parts where calcareous matter is partially disseminated, a loam of fair quality is the result; 

 and often having a reddish tinge it is not very unlike some of the least productive of 

 the Old Red Sandstone soils. (Seep. 193.) Where the quartzose conglomerates or red 

 sandstones prevail the surface is sterile, and striking examples of this may be seen in the 

 Hoar Edge, in the hills of Netherwood, Church Preen, &c, and in the higher parts of the 

 ridges extending from Horderly by War tie Knoll to Corston near Clungunford. 



The soil of the Llandeilo flags is often very good, as might be naturally inferred from 

 the composition of the rock, but as the formation is seldom well developed in Shrop- 

 shire, (being seen only partially in a region of mines to be described in an ensuing- 

 chapter,) its agricultural characters are best studied in Caermarthenshire, on the banks 

 of the Towy near Llandeilo, particularly in the beautiful domains of the Earl of Cawdor 

 and Lord Dynevor. 



In the large tracts of North and South Wales occupied by the Silurian System, there 

 are, as before explained, many districts in which calcareous matter is entirely absent, 

 and in such situations, the Upper Silurian rocks being mudstones, the quality and nature 

 of the soil may at once be understood. This argillaceous soil, usually of a dark grey 

 colour and sometimes almost black, (forming in many instances what the inhabitants 

 term " rotch" or rotchy land,) is generally cold and of little value (particularly in high 

 mountain tracts) , but where it contains a slight proportion of sand and lies upon 

 favourable slopes, it is not unproductive and is specially favourable to the growth of 



1 Notably in the hills above Downton on the rock, Mocktree Hays, &c. 



2 i 



