Mountains Castings ejected in all countries.
CHAPTER III.
THE AMOUNT OF FINE EARTH BROUGHT UP BY WORMS TO THE SURFACE.
Rate at which various objects strewed on the surface of 121 163
grass-fields are covered up by the castings of
worms The burial of a paved path The slow subsidence of
great stones left on the surface The number of worms
which live within a given space The weight of earth
ejected from a burrow, and from all the burrows within
a given space The thickness of the layer of mould which
the castings on a given space would form within a given
time if uniformly spread out The slow rate at which
mould can increase to a great thickness Conclusion.
CHAPTER IV.
THE PART WHICH WORMS HAVE PLAYED IN THE BURIAL OF ANCIENT BUILDINGS.
The accumulation of rubbish on the sites of great 164 208
cities independent of the action of worms The burial of
a Roman villa at Abinger The floors and walls
penetrated by worms Subsidence of a modern pavement The
buried pavement at Beaulieu Abbey Roman villas at
Chedworth and Brading The remains of the Roman town at
Silchester The nature of the debris by which the
remains are covered The penetration of the tesselated
floors and walls by worms Subsidence of the
floors Thickness of the mould The old Roman city of
Wroxeter Thickness of the mould Depth of the
foundations of some of the Buildings Conclusion.
CHAPTER V.
THE ACTION OF WORMS IN THE DENUDATION OF THE LAND.
Evidence of the amount of denudation which the land has 209 236
undergone Sub-aerial denudation The deposition of
dust Vegetable mould, its dark colour and fine texture
largely due to the action of worms The disintegration
of rocks by the humus-acids Similar acids apparently
generated within the bodies of worms The action of
these acids facilitated by the continued movement of
the particles of earth A thick bed of mould checks the
disintegration of the underlying soil and rocks.
Particles of stone worn or triturated in the gizzards
of worms Swallowed stones serve as mill-stones The
3