Correspondence — W. 8. Greslei/, F.G.8. 189 



2. " Some New Carboniferous Plants, and how they contributed 

 to the Formation of Coal-Seams." By W. S. Gresley, Esq., F.G.S. 



The author, in a paper published in abstract in the Society's 

 Quarterly Journal for May, 1897 (vol. liii, p. 245), argued that certain 

 brilliant black laminee in coal, and similar materials found among 

 some mechanical sediments of the Goal-measures, pointed to the 

 former existence of an aquatic plant. In the present communication 

 he describes structures in the pitch-coal lamiufe of bituminous coal 

 and in the glossy black layers of anthracite which he believes to 

 be indications of two other kinds of plants, and states that he 

 has examined structures which may be dye to some other kinds of 

 vegetation. 



THE FORMATION OF SOIL. 



Sir, — That the mode of formation of surface-soil is generally sup- 

 posed to be due chiefly to the accumulation of the dust and ashes of 

 dead vegetable matter and of animals, and their ceaseless action 

 while alive within and upon it, and to the decomposition of the sub- 

 soil or of the rocks immediately below the soil, brought about and 

 ever going on by atmospheric agencies and changes, rain being the 

 principal agent, seems a correct statement to make. But as to hoio 

 and why this soil came into existence and grows, those who have 

 studied the matter do not appear to be agreed or to have found a fully 

 satisfactory answer : for instance, one student would attribute the 

 phenomena chiefly to the action of worms ; another, to ants, 

 beetles, etc.; a third, to plant-decayed vegetation; a fourth, to 

 rock- weathering ; a fifth, to rain. Without doubt, all of these 

 have been more or less instrumental in soil-making, while the last 

 — -rain — would seem to be the one thing needful — the essential agent. 



Now it seems to me that additional light may be obtained on this 

 interesting subject if we consider it as follows : — 



(1)1 postulate that for every soaking or even moistening of the 

 surface by a shower of rain or snow, etc., which is followed by 

 a spell (whether short or long) of bright and warm weather, 

 evaporation is caused. 



(2) That such periods of evaporation imply a rising upwards of 

 a portion of the water through the soil, to escape as vapour. 



(3) That if such evaporation goes on after each shower or storm, 

 there is ever going on in the soil a downward and upward gentle 

 and invisible flow or movement of moisture, which pervades every 

 particle of the soil-forming materials, in manner somewhat analogous 

 to the flow of sap in a tree. 



(4) That water flowing or soaking among rock-particles and re- 

 mains of animal and vegetable substances must ever be changing its 

 chemical composition, and also that of the ingredients of the soil ; 

 therefore, the constant up-and-down creep or pulsative action of 

 the moisture through the solids of the soil must be working 

 a gradual change in the chemical and the physical condition of 



