353 
ing an extensive estate, observed great variations in the soils, not only 
on the sides of the hills which might have been expected, but also in the 
fields upon the table land forming the summits of these hills. Being at 
a loss to account for these variations, he mentioned the subject to a ge¬ 
ologist, who was making a geological survey of the district at the time. 
They went over the estate with a map in hand, “and marked in different 
colors the ranges of different strata of rock, as they appeared in succes¬ 
sion upon the surface, forming themselves into zones or breadths of one, 
two, or more fields together.” “ The result thus obtained clearly demon¬ 
strated that the value of each field, and the mode of cultivation already 
adopted (with the exception of the use of lime, which had been too fre¬ 
quently and too indiscriminately applied to the entire estate) corresponded 
to the variations of the strata, and were limited by the areas which these 
occupied on the surface; thus showing that (though the results had 
been arrived at by the farmers through a different process, viz : trial and 
error) the geological character of a country, when accurately understood, 
pointed out at once the natural value of the land, and the system of cul¬ 
tivation best adapted to it. For instance, on the highest range of my 
hills, a few fields, without any apparent reason, have been universally 
productive in all seasons, more so than the fields adjoining them on a 
lower level, and which appeared nearly of the same quality. The fossils 
and other marks well understood by the geologist, proved them to con¬ 
sist of an insulated portion of the upper calcareous grit formation, which 
also produces an excellent tract of land in another part of this country. 
Again, when, on descending the hill sides, it was found that there were 
certain fields which, whether toward the south or north, w r hatever the 
aspect, whatever the local circumstances, (so long as not too steep to be 
ploughed), invariably produced good wheat. It was a triumph for agri¬ 
cultural geology to discover that these fields were invariably upon the 
Oxford clay, or rather where the lower beds of the calcareous grit become 
mixed up with that formation ; and, comparing the comparative value 
and growth of timber produced upon different portions of the slopes where 
too steep for ploughing, it was satisfactorily established that oaks flour¬ 
ished the best upon this identical stratum or zone wherever appearing.” 
Prof. Johnston, when speaking of the lower silurian rocks, remarks : 
“ In this formation, as in every other we have yet studied, the soil 
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