480 Transactions. 



analytical results in the appendix we find (1) that a low percentage of potash 

 is characteristic also of the " Old Brown " formation of the valley-gravel 

 series, so also a low percentage of CaO and MgO ; (2) that P 2 5 is not 

 phenomenally low— average for greensands, 0-21 per cent. ; average for 

 other formations, 0-20 per cent. 



It is further stated that " The dark sand seems to be differentiated by 

 a much lower content of potash and phosphoric acid." This statement, 

 however, is not justified by the analyses of the four soils given, for the 

 figures for potash are 0-24, 0-13, 0-18, and 0-23, two of these being quite up 

 to the average of the brown sands ; while the figures for phosphoric acid 

 are 043, 0-11, 0-19, and 0-16, one of these being exceptionally high and 

 at least one other not exceptionally low. 



The percentage of CaC0 3 is admittedly phenomenally low (average 

 0-08 per cent.) ; but the Old Brown valley-gravel soils have only 0-11 per 

 cent., the- Oxford clay formation only 0-12 per cent., and a Gault formation 

 only 0*15 per cent. Moreover, in the discussion of the " characteristic 

 properties and agriculture " of the various soil formations there is no 

 mention of the necessity for liming or of an excessive use of artificial 

 manures. On the contrary, it is stated that, though " the dark sand 

 formation is characterized by very low percentages of phosphoric acid, 

 potash, and calcium carbonate," it is nevertheless " reported by market- 

 gardeners as being not quite so ' hungry ' as the brown sand formation." 

 Again, the table of distribution of crops shows that the main crop is early 

 potatoes, which are " associated with brown and dark greensand and 

 valley-gravel soil formations," while it is stated also that the success of 

 the crops depends to a large extent on the rainfall. 



The present writer therefore submits- — (1) that a unique chemical 

 composition does not characterize this soil formation ; (2) that the chemical 

 composition of the soils of the formation does not in any way affect their 

 agricultural utilization or treatment ; (3) that the only agricultural feature 

 of the formation apparently connected with geological origin is the high 

 percentage of coarse sand ; but that (4) this is not an invariable feature 

 of greensand-derived soils, for Hall and Russell find that " the soils [of the 

 Upper Greensand in Kent, Surrey, and Sussex] are well balanced and 

 contain all the fractions suitably developed . . . the soils always 

 show a sufficiency of carbonate of lime." The Folkestone sand, however, 

 is " coarse-grained and devoid of carbonate of lime." 



Rigg's next illustration is the Oxford clay series. This is divided into 

 two soil formations — (a)' pure-clay soils, (b) clay loams. " The results of 

 chemical analysis," he says, " are sufficient to distinguish the Oxford clay 

 series from all the other clay formations dealt with in this paper, for the 

 percentage of calcium carbonate and phosphoric acid is extremely low in 

 all the samples taken from this series." 



The analyses submitted, however, in no wise support the assertion, for 

 the percentage of phosphoric acid for the clay loam formation averages 

 0-13 per cent., which compares with the average for the dark greensands 

 (0-15 per cent.), the heavy valley gravels (0-17 per cent.), the boulder clays 

 (0-17 per cent, and 045 per cent.), and the brick-earths (0-14 per cent.), 

 while the CaC0 3 for the samples given is 047 per cent., 070 per cent., and 

 0-06 per cent. As for the pure-slay soils in this series, it is scarcely fair to 

 generalize, seeing that the analysis of only a single sample is given. Moreover, 

 one of the three samples of clay loam analysed shows only 0-06 per cent, of 

 CaC0 3 , a feature which has been cited as characteristic of the greensand 



