The yellow colour marks a sedimentary deposit, brown is oil shale and reddish brown is limestone.
The fuel crisis due to war resulted in a search for alternatives to coal, wood and peat. Back in 1908, oil shale had been found in Jõhvi parish, in Järve municipality, lying in layers of varying thickness over 8-10 square kilometres. In 1916, geological investigations led by the Petrograd fuel head committee continued in the area, near Rakvere-Jõhvi railway. Shafts dug into several places showed that an extraction site near the municipal building in Järve village was the promising site, where oil shale deposits were even exposed on the ground surface. Experiments found that the oil shale could be used as a fuel for residential and industrial use, including the railway. Up until spring 1917, about 50,000 poods of oil shale was extracted in Järve village.
Oil shale didn’t solve the fuel crisis, as mining was not nearly massive enough. There was a lack of machinery and manpower. Only the Aseri and Kunda cement plant decided to change over to oil shale as a fuel, as there were no other possibilities for keeping the plants running.