282 Fiirf/ier Studies on the Soils of North Wales 



Conclusion. 



Many of the soils of this paper do not differ greatly from the soils of the 

 adjoining parts of P^ngland and, since they are found in the regions of 

 North Wales which have the lowest rainfall, they are not so typical 

 as those described in the former paper. The Carboniferous and Millstone 

 Grit soils are the only sedentary soils examined in the present paper. 

 The sedentary soils of the older Palaeozoic formations showed the 

 rather remarkable fact that the coarsest fractions were not generally 

 the richest in silica. While we have, not made determinations of the 

 composition of the fractions of the sedentary soils of this paper, yet it 

 is obvious from inspection that they are exactly similar to the majority 

 of soils hitherto examined elsewhere in that their coarsest fractions 

 consist almost entirely of quartz sand. In fact the character of the 

 coarse fractions forms a useful criterion for distinguishing between these 

 soils and the older Palaeozoic soils. 



The general poverty in calcium carbonate is noteworthy. Even some 

 of the soils derived from the Carboniferous Limestone are lacking in 

 this soil constituent. This is rather remarkable when it is considered 

 that some of the chalk soils examined by Hall and Russell in their 

 survej' of Kent, Surrey and Sussex are formed under rainfalls at least 

 as great as that in some of the limestone districts of our area. The 

 matter is at least worth investigation. 



Even the very sandy soils contain reasonable quantities of potash. 

 This as was suggested elsewhere^ is doubtless due to the presence of 

 potash minerals in the finer fractions. Although the soils described 

 above are considerably younger than the typical Palaeozoic soils, they 

 differ to some extent from the soils of S.E. England whose particles have 

 undergone numerous vicissitudes of weathering, sorting and dej^osition 

 which have resulted in their soluble constituents being leached out. 



It is a fortunate circumstance that the heaviest clays in North Wales 

 occur under the driest climate. We are not prepared to say that this 

 is quite fortuitous but the exact connection, if any, is not qxute clear, 

 and needs further consideration. Were clays as heavy as those of the 

 Vale of Clwyd to occur in the wetter hill districts, it is difficult to see 

 how they could be worked. 



In conclusion, we would thank, besides those gentlemen mentioned 

 in the earlier paper. Mr G. J. Williams, H.M. Inspector of Mines and 

 Quarries, and Mr Edward Greenly, the author of the Anglesey Geological 

 Survey, for their kind counsel on geological questions. 



• "Soils of North Wales." G. W. Robinson. Juurii. Bd. uf Aijn'c. June, 11115. 



{Received April 22nd, 1919.) 



