Wild. — A Soil Survey of New Zealand. 483 



properties. The characteristic properties cited by each for the same forma- 

 tion are. however, frequently the exact opposites of one another, although 

 the soils examined were in adjoining comities. Thus Rigg shows that 

 Oxford clay soils are poor in calcium carbonate, while Foreman proves 

 that they are rich in that substance. Both quote the Gault clay as 

 extremely rich in CaC0 3 , while Hall and Russell say, " The most typical 

 Gault soil is deficient in calcium carbonate : all the samples analysed show 

 less than 0-05 per cent, of calcium carbonate, except No. 30." 



These results certainly do not furnish convincing proof that a given 

 geological formation gives rise to a soil differing consistently from the 

 soil derived from another geological formation. In Cambridgeshire, for 

 example, there are clay soils from five different geological formations, but 

 these soils do not differ in really important characters, and such differences 

 as do occur are frequently not carried consistently even into the adjoining 

 county. 



Foreman will now be followed in his account of the other properties of 

 these soils described by him. For convenience of comparison these are 

 brought together into a concise summary. 



A. Soils of the Boulder Clay. 



1. Colour: " Brownish." 



2. Texture : " Extremely tenacious." Almost impossible to obtain a satis- 



factory tilth, except in very good seasons. 



3. Crops : Barley, oats, wheat, clover, beans, or mangolds — -fair to moderate. 



Undrained land carries very poor pasture ; greatly benefited by basic 

 slag. 



4. Weeds : Abundant — (1) Avena fatua, (2) Ranunculus repens, (3) Brassica 



sinapis, (4) Sonchus arvensis, (5) Carduus arvensis, (6) Carduus 

 acaulis, (7) Rumex crispus, (8) Galium Aparine, {9) Agrostis stolonifera. 

 In small quantity — (11) Stellaria media, (12) Senecio vulgaris. 



B. Soils of the Gault. 



1. Colour: Light ("thus readily distinguished from those of boulder 



clay "). 



2. Texture : " Very stiff and sticky " ; " difficult to till, a bare fallow is 



absolutely necessary at frequent intervals." 



3. Crops : Wheat, clover, barley, oats — fair crops in favourable seasons. 



4. Weeds : Abundant — (13) Taraxacum dens-leonis, (14) Tussilago farfara, 



and (2), (5), (7), (3), above. In small quantity — (15) Euphorbia 

 Peplus, (16) Geranium molle, (17) Veronica agrostis, (18) Potentilla 

 reptans, (11), (12), above. 



C. Soils of the Kimeridge and Ampthill Clays. 



" Ampthill clay very closely resembles Kimeridge clay, and the 

 soil derived from it was similar to those from the Kimeridge in every 

 respect." 



1. Colour: Dark brown. 



2. Texture : " Very stiff, sticky, and troublesome, necessitating a frequent 



bare summer fallow." 



3. Crops : Wheat, oats, clover, beans — -fair to moderate. 



4. Weeds : Abundant— (1), (14), (3), (5), (6), (7), above. Fairly prevalent 



-(13), (11), (8), (16), (17), above. 



16* 



