28 THE ESSEX NATURALIST
by the nature of the soil: it grows better in the loose, sandy soil
than in the more compact clay soils.
To summarise, two types of soil combined with a particular
topographical pattern, produce a zoning of the canopy, and
this latter factor, together with the others, produces a zoning
of the field layer, all these inter-relationships being very well
demonstrated in Woodham Walter Common.