Indications of the Fertility or Barrenness of Soils. 439 
the stones not too soft, or too small, nor too thick on the top- 
soil ; and the top-soil of a firm texture. On the other hand, 
if the top-soil is inclined to look dark and moory, and appears 
comparatively free from stones on the top, we expect this to be 
sour, weak land ; or if we find the stones in the subsoil of a soft 
texture, a pale colour, and a quantity of small stones lying on 
the top-soil, we judge this to be weak land, but healthy for sheep- 
stock ; also, if we find the subsoil to consist of a flat, compact 
rock, we say this is not a fertile soil ; and the nearer the rock 
approaches the surface the worse it is. What renders this soil 
unproductive is, that the roots of the plants cannot penetrate the 
rocks to the requisite depth, neither can the water percolate 
sufficiently quick, nor the moisture ascend readily in dry weather. 
Many of these flat rocks lie immediately under, or upon, a bed 
of clay. If we find clay on these hills we do not pronounce the 
soil good, notwithstanding the stone should be hard and good. 
In a general way, the harder and firmer the texture of the stone 
the better the land, provided the subsoil be loose, and not reten- 
tive of water. 
I fear my observations will be found too lengthy and tedious 
for a work of this nature, therefore 1 shall treat of only one more 
district of country, and that on the lias formation, which runs (as 
far as I have traced it) from Bristol, through the vale of Glou- 
cester, part of Worcestershire, and on into Warwickshire. Some 
persons call it the blue lias, and certain it is that all the stone 
which it contains has, more or less, a blue cast. The harder it 
is the bluer it is ; that which is soft is of a pale colour ; but the 
beds of clay are of many colours : some are red, containing 
gravel and sand of the same colour ; some are almost white, with 
much lime-wash in it, having the appearance of mortar ; others 
are yellow and blue, and between the bottom beds of stone there 
is a blue marl. This being the composition of the lias forma- 
tion, it must, in consequence, produce supersoils of various 
colours, as the different beds of stone and clay come to the sur- 
face, or (to use a geological phrase) crop out ; and such is the 
case for the whole district of country I have mentioned. There 
is another material cause of the difference in colour in this forma- 
tion, which is this : in many places here are banks, or (perhaps 
more properly and correctly speaking) continuations of some ex- 
tent from the oolite, which run, in some instances, for miles on 
this formation ; and in other parts there are detached spots of 
alluvium, left by the water at some time. These facts, combined 
with the natural formation of this strata, must consequently pro- 
duce many qualities of land, and those of many colours. 
We have some good land, and some very bad in this district, as 
may be supposed from the above description ; but, I believe, the 
