388 Market -(Tardea Soih (tml Crops 



possesses little ac;;ricultural interest, Hall and Russell made only a very 

 rough division into areas of dift'ercnt texture. 



In the market-garden district dealt with in this paper there are 

 large areas where the texture of the original soil has been greatly 

 altered by alluvial wash; there are very extensive valley gravel 

 deposits which are subject to varying texture and structure; and lastly 

 boulder clay deposits give rise to soils in some cases (juite different 

 from the majority of boulder clay soils. 



Since market-garden crops, as will' afterwards be shown, are sus- 

 ceptible to even slight variations in soil texture, it became necessary 

 to map out the extent of ail variations occurring on the geological 

 formation before any correlation of crop and soil could be attempted. 



The writer has followed Hall and Russell in using the geological 

 formation to mark the extent of a series of soils which have a somewhat 

 similar mineral structure. These series of soils have, however, then 

 been separated into soil formations having different agricultural 

 properties and the extent of each has been mapped. 



For the purpose of mapping the soil formations, the six incli ( )i diiance 

 Survey maps, which show the fields, were used. Every field was 

 examined in a detailed way over the whole area. Field ol>servations 

 of the colour, texture, the agricultural operations and general surface 

 features were used in determining the extent of each soil forniation. 

 The six inch maps were then reduced to the one inch scale from 

 which map 4 was constructed showing the various soil formations in 

 the district. 



The following geological formations were examined and the series 

 of soils occurring on them were divided into soil formations which had 

 different agricultural properties : 



(1) Oxford clay giving rise to two soil formations: 



(a) Pure clay soil, 



(b) A clay loara probably resulting from an alluvial wash 

 on to the clay soil. 



(2) Oreensand giving rise to two soil formations: 



(a) Dark sands, 



(b) Brown sands. 



(3) Gault giving rise to two soil formations: 



(a) Pure clay soil, 



(b) A sandy loam locally known as "Redland," occurring 

 as a narrow strip between greensand and the ])ure gault 

 clay soil (a). 



