two thick seams, separated by about 9 fathoms of rock , chiefly sandstone. These seams vary from 6 to...series, and under more than a hundred fathoms of rock, in which are many small seams of coal and some...the extremities of the field . separated by sand rock . There are two principal divisions of the series...of trees ; often though brown they appear in the mine like coal, and may be worked in the same way, but...corresponding much more with real coals . When seen in the mine, or recently brought out , they are bright, black |