10 A. R. Horwood — Rock-soil and Plant Distribution. 



carried out b^' the State. This opinion lias, in fact, already been 

 stated by ecologists. This necessity of course arises primarily from 

 the purely ecological value of the work, and since ecolo<i y and geology 

 are, as I have shown, interdependent, there is thus additional reason 

 for urging that the former be recognized, as fully as the latter, as 

 of national importance, and therefore worthy of public support of 

 a financial kind. 



It is therefore suggested that till this is accomplished, if it meets 

 with approval in this quarter, geological survey work should be 

 definitely carried out in conjunction with ecological surveys. Soil 

 surveys have been made in conjunction with experimental stations at 

 the instance of the Geological Survey, and the further step I advocate 

 in this direction would be of a similar kind and for a similar purpose, 

 though on a wider basis. At anj' rate it might be possible that those 

 at work in each district, upon ecological surveys, should be asked to 

 co-operate, where required, with geological surveyors, especially in. 

 those areas where this co-operation would be of great assistance 

 in tracing boundaries of local beds. 



It is further suggested, if this be possible, that a definite effort 

 should be made to accomplish the appointment of Government 

 ecological surveys by those already officially in charge of geological 

 work, in view of the assistance each science can render the other. 

 Whilst emphasis has been laid here on tlie value of ecology to the 

 geologist equal value is rendered of course by the geologist to ecology, 

 and speaking as a geologist I might even say more. It must not be 

 forgotten that, though little of this figures in literature, there are 

 men who have for long noticed the connexion between plant dispersal 

 and rock conformations in their systematic survey of the geological 

 structure of the British Isles, if 1 mention only Sir Archibald Geikie 

 and Mr. H. B. Woodward. A few examples of the data afforded by 

 plants as to geological horizons may serve as an appendix to these 

 remarks, but only a brief summary can be given and a selection of 

 certain formations made. 



Carhoniferous Limestone. — Ash woods are the typical woodlands and 

 would at once mark off a limestone district from a sandy district with 

 sessile oaks as in Derbyshire. In such woods there is a predominance 

 of one or two plants, such as Mercurialis perennis, Adoxa moschatellina, 

 Lamium gahohdolon, etc. The open grass land of the massifs is 

 characterized by such plants as Reseda luteoln, Arenaria verna, 

 Geranmm lucidum, A?ifhi/llis vulneraria, Saxifraga tridactylites, 8edum 

 acre, Helianfhemum, Galium aspermn, Origanum vulgare, Thi/mus 

 serpgllum, Mahenaria viridis, Allium vineale, Koeltria, Bracliypodium 

 pinnatum. Where these plants occur, if no exposures were available, 

 limestone could be mapped, and even if only one or two of the 

 specially characteristic pUints occurred this would be enough, so 

 strong is their attachment to lime soils and their absence so well 

 marked upon others. 



In the case of the Keuper the uniform marl tracts are characterized 

 more especially as being really more clayey and loamv than marly by 

 oak woods with a particular ground flora. But the flora is rather an 

 ordinary type, and is valuable in indicating rock formations where two 



