Footpath degradation of the Malvern Hills - Malvern Hills Conservators

Stephen Britnell
Footpath degradation of the Malvern Hills
Figure 7. Techniques to measure slope angle and path angle
3.4 Method of dry sieving
Wet soil samples are transferred from the sample bags into pre-weighed containers
and dried in the open air. Due to the drying processes the soil particles cement together and
must be broken down into individual particles, this process is completed using a pestle and
mortar. Prior to sieving the sample is weighed using a top ban balance accurate to 1/100 th of
a gram, and the weight of the container subtracted to give the total weight of the sample. The
sample is then sieved mechanically for ten minutes in a set of sieves ranging from –3phi to
>4phi. The material from each phi size is then placed into a pre-weighted container and
weighed, and the weight of the container subtracted to give the actual weight of the sample.
The % of total weight for each phi size is then calculated using the following equation:
% Weight = Weight of phi sample
Total sample weight
Cumulative % is found by simply adding up the % weight of each phi size, from small (>4phi)
to large (-3phi). The % weight is then plotted against phi size to give a particle size distribution
curve, which shows the degree to which the soil is made up of clay, silt, sand, and gravel.
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