THE CONTINENTAL FLORA OF SOUTH SWEDEN 267 



»Diese Auswaschung ist in grossen Gebieten so bedeutend, dass die Ackererde 

 auch in ausgepragten Kalkgebieten so kalkarm geworden ist, dass die Ertrags 

 faiiigkeit vvestntlich dadurch herabgesetzt worden ist. Man hat dem nunmehr 

 endgiltig durch Mergelung des Bodens abgeholfen, was in der Weise geschehen 

 ist, dass man sich in den unteren, noch kalkhaltigen Moranen und Tonschichten 

 heruntergegraben hat». 



For Norrland (Jamtland) Hesselman (191 7 a) and Tamm (19 14 and 1920) have 

 proved such a considerable washing out of the upper layers on a level surface 

 that a decided podsolization may arise in strongly calcareous soil. 



It appears from wliat has been said that in the parts of South Sweden where 

 precipitations arc plenteous, there is probably a rather great washing out of the 

 upper layers going on. We cannot expect localities suitable for the species in 

 question to exist in western Sweden in the same high degree as the more cal- 

 careous types of soil above mentioned. Thanks to the latter, however, localities 

 of this kind may arise, even if they arise more or less edaphically, namely on 

 hillsides. Often the calcareous ground-water reaches to the surface or comes 

 near it on such hillsides and causes different changes in the soil with a more or 

 less decided mould-profile as the result. Owing to the more powerful exposure 

 alone more favourable conditions should exist on the hillsides. 



In a summary of the data enumerated above regarding the nature of the soil 

 of such localities in South Sweden where continental species are found, the 

 following points must be emphasized : 



1. The humid climate of South Sweden is not developed to extremes. The 

 chemical composition of the weathering soil and the topography may thus in a 

 high degree influence the nature of the soil. 



2. Soil-types of a nature evidently suitable for continental species are in the 

 first place found in connection with the occurrences of calcareous rocks, espe- 

 cially on the moraines formed by the latter (Oland, Gotland, Skane, Ostergot- 

 land, Vastergotland, Narike, Uppland). 



3. Marine sediments (clays) with a more or less great amount of lime are 

 widely distributed in plains that fall below the uppermost marine limit. However, 

 their importance would seem to be highly decreased by the fact that they are 

 often situated fairly deep down, and also by the fact that a pretty considerable 

 washing out of the upper layers has probably taken place in western Sweden, 

 where precipitations are abundant. — Above the uppermost marine limit there 

 are occurrences of comparatively limerich ice-lake clay, especially round the south 

 end of Lake Vattern. 



4. The importance of topography with regard to the nature of the soil rests 

 in the fact that, on hillsides, a ground water containing electrolytes may pene- 

 trate to the surface and influence the formation of the soil, also in the fact that, 



