302 • BOARD OF AGRICULTURE. [Jan. 



"which are practically soilless. In some cases the absence of 

 glacial waste which may afford the foundations of soil is due 

 to the steepness of the slopes on which the detritus origi- 

 nally rested, but from which it has been removed by gravity, 

 aided by the rains, the frost, and the shoving action of plant 

 roots. In other cases the lack of detrital material is due to 

 the scouring action of the subglacial streams, or to the fact 

 that the detritus from soft rocks has been altoo-ether jjround 

 to fine detritus by its contact with harder material, and 

 washed away. 



It DQt infrequently happens that the bed rock, when worn 

 by a glacier, readily breaks, on account of its natural joints, 

 into large fragments, while these fragments, in themselves 

 of a tough nature, do not readily pass into the state of fine 

 detritus. Under these conditions the surface may be covered 

 by very large angular fragments, there being insufiicient 

 finely divided material to fill the spaces between them ; and 

 thus the soil covering may be practically wanting, or reduced 

 to small patches crowded in the interspaces between the 

 large erratics. An instance of this nature may be found 

 in the " Dogtown Commons " of Cape Ann. 



We shall now consider the process by which detritus, 

 accumulated on a country by glacial action, forming pseudo- 

 soil, may be converted into a real soil coating. In an 

 ordinary soil, whether it be originally formed on the surface 

 which it occupies, or whether it has been transported by the 

 action of rivers and accumulated in the shape of alluvial 

 plains, the process of disintegration of the rock goes on 

 alono; with the growth of vegetable life ; and the debris of a 

 mineral sort is thoroughly commingled with the vegetable 

 waste, and all parts of this waste are subject to the solvent 

 action which is brought about by the decaying vegetable 

 matter. In the case of river alluvium, the vegetable matter 

 is commingled by the process of sedimentation with every 

 part of the mass. In the case of soils which originate where 

 they lie by the decay of the bed rocks, the breaking up of 

 the under strata is to a great extent accomplished by the 

 action of the plant roots, which penetrate into the rifts of 

 the strata, enlarge and rupture the fragments, and gi'adually 

 lift them to a higher level in the soil. In any forest-clad 



