||Slope classes are defined in Table 2. The optional word ‘inclined’ is used to distinguish
slope from other attributes, for example ‘gently inclined footslope’ from ‘gently
undulating rises’, and ‘moderately inclined hillslope’ from ‘moderately spaced streams’.
The class boundaries given in Table 2, and repeated in Table 4, are simply boundaries
separating slope terms in common use, adjusted to regular logarithmic intervals. They
do not refer to observed natural clustering of slope values, since such clustering
has not been shown to occur; nor do they relate precisely to boundary criteria for
land use, which vary arbitrarily between organisations and which may change with advancing
It may sometimes be advantageous to split each of the classes ‘very gently inclined’,
‘gently inclined’ and ‘moderately inclined’ into two levels, the appropriate boundary
values being 1.8%, 5.6% and 18%.
There may also be compelling reasons for using other schemes of slope classes. However,
schemes that do not have constant class widths from low to high slope values can lead
to problems in subsequent statistical work.