266 R IK A RD STERNER 



Gastrikland. Silurian limestone occurs on Limon, outside Gavle. On the coast up 

 to a level with Ockelbo in the north there is clay marl. 



Dalarne. In aring-like region round Lake Siljan there is Silurian limestone, which 

 in places nearly reaches the surface (especially in the parishes of Boda, Orsa, 

 Rattvik, Ore, and on Solleron). Within the Boda valley and in the valley from Ore 

 towards Orsa in this district the marl has a high percentage of lime (15 — 17 %). 

 Moraine clay and moraine gravel with an average lime percentage of 4 is also found 

 in the Archaean rock district south-east of Lake Siljan (in the parishes of Leksand, Al 

 and Bjursas). 



Vdrmlaud. The clays on the shores of Lake Vanern are poor in lime. 



In this survey the greenstones have not been mentioned. Yet they may lo- 

 cally be of great importance. Concerning their distribution the zone of hyperite 

 occurrences in western Sweden may be mentioned. It stretches all through cen- 

 tral Varmland, through Vastergotland and western Smaland down to northern 

 Skane. In Smaland, however, hyperite occurrences are scarce. (Compare Hard av 

 Segerstad 1920, Ringius 1888, and Tamm 192 [). 



In large parts of the plain of South Sweden there are consequently more or 

 less strongly calcareous types of soil. — From a phytogeographical point of 

 view, — as has been said above — the importance of these lies not so much in the 

 fact that they contain rich quantities of » nutritive salts* as in the influence of 

 the latter on the chemical changes in the soil and its development from a phy- 

 sical point of view. It is here, however, that the lack of investigations stands 

 out most clearly. 



In accordance with the comparatively plenteous precipitations and scanty eva- 

 poration there would seem to be a downward water-current in the ground in almost 

 the whole of South Sweden. Hence more or less soluble salts are carried away 

 from the upper layers. If this transference is active enough, and if no new quanti- 

 ties of salts are supplied, the upper layers ought sooner or later to be leached. 

 For this reason it is conceivable that the upper layers may be very poor in 

 electrolytes, while the latter are plenteous in deeper layers. It is then not so 

 much the mere occurrence of a calcareous type of soil that should be examined, 

 as just the nature of the upper layer, where the plants are generally rooted. 



We have no detailed knowledge of how far there is such a washing out of 

 the soil in South Sweden. In the accounts of the clay districts of the West 

 Coast published by the Geological Survey of Sweden it is said that, on the 

 calcareous clay, there rests a layer of limeless clay to a depth of one or two 

 feet. This layer is interpreted as a layer of striped clay which has been washed 

 out. (See the descriptions appended to the >Halmstad» and »Varberg» map- 

 sheets.) 



Andersson und Hesselman (19 10) ascribe to the washing out a very great 

 importance with regard to the nature of the soil in the arable land. They say: 



