406 MR. II. B. WOODWARD ON THE SOILS AND SUBSOII S OF NORFOLK. 
Fortified with a sound general knowledge of his subject, he 
commenced work at Norwich, where, as he says, “ I found the 
variations of soil so sudden, so frequent, and apparently so 
arbitrary, that I almost despaired of reducing them to any law.” 
He, therefore, appealed to the cliffs of Cromer, which might not 
now be regarded as the best preparation for definite classification, 
and thence strove to carry out his “purpose of laying down the 
variations of soil upon the Ordnance map.” He tells how in little 
more than a week he gained confidence and formed a theory ; but 
as he advanced into South Norfolk he was at fault. “ Clay 
occurred where I expected to find sand, and sand where I looked 
for clay.” Then he “ repaired to the coast sections at Gorleston, 
and the river sections of the valley of the Waveney, and found 
that these apparent exceptions were likewise a consequence of the 
law, and proved its truth.” Having thus examined the eastern 
half of the county he “ passed more rapidly over the remainder, 
making wide traverses, and ceasing to map the surface variations.” 
Although I am not aware that any of Trimmer’s maps have 
been preserved, there can be no doubt that his main work was to 
map the subsoils, meaning thereby the solid sti'ata and the drift 
as they appear at the surface. As he remarked, the scale of the 
(one-inch) Ordnance map is the smallest on which these variations 
can be shown, and he illustrated them by means of sections. 
In a later paper, published in 1850, Trimmer made “Proposals 
for a Geological Survey specially directed to Agricultural Objects.” 
In this work he adopted a classification into Local, Alluvial, and 
Diluvial or Erratic soils. The Local soils were “ those derived 
wholly from the decomposed materials of the subjacent stratum, 
represented in ordinary geological maps as constituting the surface.” 
The Alluvial soils were those belonging to river and estuarine 
deposits, including peat bogs and blown sands ; while the Erratic 
soils were those derived from the Drifts. Such a classification is 
not in accordance with our present ideas, inasmuch as the three 
divisions are equally to be regarded as local ; the alluvium bordering 
our rivers, and the various drift deposits yield their local soils just 
as much as the more regularly disposed solid strata. The 
exceptions, as before mentioned, are the materials washed down 
slopes and those which are wind-drifted. 
Trimmer did excellent work in calling attention to the im- 
portance of a systematic survey of all the superficial deposits 
