392 Markt't-Gardo) Soih and Cropa 



Relationship of Soil Formations to Surface Geology. 



It is of some interest to compare the soil foiinations with the 

 geological formations and to ascertain the agencies which have produced 

 varying types of soil, and maps 2 and 4 have been drawn to the same 

 scale in order that the two sets of formations may Le readily compared. 



The geological map has been pieced together fniin iiumcroiis six- 

 inch maps which the (Jeoiogical Survey Office kindly placed at my 

 disposal. The lower half of the map has been published on the one 

 inch scale, but the only maps obtainable for the upper half were the 

 unpublished draft sheets at the Survey Office. Under these circum- 

 stances it is probable that the accuracy of the geological map is not 

 very great in minor details, for this map has not been revised since 

 the first survey was made. 



In the case of boulder day cappings resting on greensand, two 

 small areas, marked B^, D on the geological map 2, seem to have dis- 

 appeared. It is quite probable that the thin capping of boulder clay, 

 once existing here, has been disturbed by coprolite digging. 



Again, two areas A, A^ are marked on map 2 as belonging to the 

 brown valley gravel soil foniiatioii but the geological uia]i shows boulder 

 clay and brick earths in these two spots. There appears to the present 

 writer to be considerable evidence for mapping the geology of these 

 areas as valley gravels. The surface features point clearly to these 

 areas as a continuation of the main valley gravel formation marked A^, 

 map 2. The valley gravel formation is certainly continuous over 

 the area A and, in the case of the area A^, there is only a narrow 

 depression of cla}^ separating it from the main area A^, map 2. The 

 area A^ moreover is an elevated gravel soil which appears undoubtedly 

 at one time to have been linked up with the main area A^. Gravels 

 consisting of broken flints have been dug up from both the areas A and 

 A^ and these gravels are exactly similar to those underlying the main 

 gravel soil formation A'-, map 2. A comparison of the following 

 analyses reveals the similarity of the topsoil and the subsoil of 

 the supposed valley gravel areas A and A^ with the main valley 

 gravel formation A^, map 2. Analyses of brick earth and boulder 

 clay soils in the vicinity are also given for purposes of comparison. 



Not only does the analysis of the supposed valley gravel topsoil 

 agree in every respect with that of the known valley gravel soil, but the 

 subsoils are also identical and are widely divergent from the boulder 

 clay and brick earth soils in the immediate vicinity. Since the geologist 



