397 
Figure 7: Active opencast site Figure 8 : Derelict opencast site 
excavation is found large dumps of overburden while dumps of soil may "be 
seen in remoter parts of the site* The two dumps are differentiated "by- 
size, tone (the soil is usually darker) and often texture (the 
overburden is coarse, due to its "blocky structure)* In addition, active 
sites (Fig* 7) have mobile plant in the form of dragline and other 
excavators, bulldozers and trucks, and site offices* A disposal point 
where coal is prepared and distributed may also be present. Where a site 
has been reclaimed, its appearance will be anooth in shape with varied 
tones resulting from revegetation, and a regular pattern of drainage 
channels will often be found. The opencast site shown in Figure 8 is 
derelict but shows some signs of natural drainage and vegetation 
development, although not to a satisfactory degree* 
In conclusion to this brief description of mining and its forms as 
seen on the aerial photograph, mention must be made of a comparatively 
recent development, that of rewashing. Old spoil heaps contain a high 
proportion of coal (which is why they are likely to spontaneously ignite) 
as result of less efficient washing procedures in early mines. Many of 
these tips, where derelict, are now being rewashed for the coal content* 
This usually takes place in situ and as nothing remains of the old mine 
the only features apparent are the newer and smaller washing plant, site 
offices, mobile trucks, and a generally disturbed area around these. The 
spoil heaps resulting from the rewashing are often darker toned than the 
original tips since they contain more moisture, and are finer textured* 
Being less consolidated than their predecessors they also show signs of 
gullying and a general lack of vegetation. 
Survey Results* 
The form in which the survey data was presented has been discussed 
under Survey Procedure. Ro detailed analysis of the data has been under 
taken since the current research has been concerned with developing the 
survey method and examining the problems involved with all stages of the 
work. Table I, however, summarises the data transferred to the Welsh 
Office survey forms, i*e., for all sites greater than 1 ha. in area* The 
figures refer only to actual spoil heaps, excavations and buildings and 
do not include the degraded ground level areas surrounding those features. 
The inclusion of such areas will probably cause a significant increase in 
the totals although the amount of increase cannot be ascertained at 
present• 
Total area of all derelict sites 
Total area of all actively disfigured sites 
Total area of spoiled landscape 
Percentage of Administrative County which 
is spoiled 
Table I: Spoiled Landscape in Glamorgan, 1971* 
The last available statistics for 1969 (Welsh Office, 1970)» when 
only true dereliction was surveyed, indicates a total area of 2,914 ha 9f 
a difference of 3»561 ha. The increase in the 1971 situation is probably 
4,176 ha. 
2,299 ha. 
6,475 ha. 
3 . 4/0