Another similarity with the Maardu mine concerns saving mining process data. Today only few maps and documents are available about the Maardu mine. Mapping its underground part is almost impossible due to the lack of map and other information, caused by changes in the enterprise ownership. The same situation could easily happen to oil shale industry. This brings out another aspects of the importance of the present study - saving information in an easily accessible form for the future.
Aerial photographs show it as a striped area.
The third one is a graded area, mainly without vegetation but ready for planting. Figure 5 Reclamation dynamics of Sirgala open cast area Oil shale surface mining has influenced northeastern Estonian landscape since the first days of oil shale industry. Which of these stages has been best for recovering the nature, is a question for ecologists. In surface mines the same range of equipment is used for stripping low-bedded deposits as for construction, amelioration and agriculture. This limits the oil shale mining area where such technology could be used to the bedding depth from 2 to 10 m.