Most of the coal mined today was formed from plant material accumulated in swamps and peat bogs during the Carboniferous period about 300 million years ago.
(coal; mined; T:today) (Most of the coal mined today; was formed; from plant material) (plant material; accumulated; L:in swamps and peat bogs; T:during the Carboniferous period about 300 million years ago)
coal Most of the coal mined today plant material
mined was formed accumulated
T:today
from plant material
L:in swamps and peat bogs T:during the Carboniferous period about 300 million years ago