138 Prof. Johnson’s Repert on the Bradford Coal Field. 
valley of Towanda creek. On this creek itself, the lower beds 
of limestones, sandstones and shales underlying the coal measures 
are found at a high angle of inclination, often dipping not less 
than 40° or 50° towards the south or southeast. On the easterly 
and southeasterly parts of the coal field, on the contrary, the dip 
of the lower rocks is to the west or northwest, while on the 
southwestern parts, especially on Burnet ridge, the slope is evi- 
dently towards the north. ‘ The coal measures lie on both sides 
of the Carbon creek, the valley of which, as well as those of its 
tributaries, is a valley of denudation, made by the action of water, 
which at the northeastern extremity of the coal basin has exca- 
vated its channel through the whole coal series, over two hun- 
dred feet thick, and to a depth of more than seven hundred and 
fifty feet below them, into the underlying strata of slates, lime- 
stones, sandstones and shales, 
Great pains appears to have been bestowed by Prof. Johnson, 
in determining by actual survey and levelling, the true elevation 
of all the important points where any of the mineral deposits are 
opened. ‘This was rendered necessary as well by the wilderness 
and uncultivated condition of the country which prevented ex- 
tended observation as by the generally level position of the strata 
which rendered it often difficult to determine the dip in the ordi- 
nary manner. 
It appears that the main beds of coal in the Bradford district 
are two, one of from five to seven feet and the other from thirty 
inches to three feet in thickness with some intermediate plies of 
less value. They lie about one thousand one hundred and twelve 
feet and one thousand two hundred and nineteen feet respectively 
above the level of the Susquehanna river at Towanda, distant 
from ten to fourteen miles. The miueral deposits constitute the 
upper portions, in the nature of outlying masses of the formation, 
and all the streams which intersect the coal field are found in so 
many valleys of denudation, which being wider above than below, 
have of necessity, destroyed more of the upper than of the lower 
beds of coal. This coal field, like nearly all others whether in 
_ this country or elsewhere, abounds in the argillaceous carbonate 
of iron and in seams of fire clay. Calcareous conglomerates are 
peace seen at different elevations, but no considerable body of 
hee yet been developed immediately within the 
