'The rocks of the Carboniferous period provide the Earth with this, some of it bituminous'
coal
PERIOD: The rocks of the Carboniferous period provide the Earth with this, some of it bituminous
The rocks of the Carboniferous period provide the Earth with this, some of it bituminous
The rocks of the Carboniferous period provide the Earth with this, some of it bituminous
PERIOD
coal
PERIOD