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Table 6.—Ratios of developed to original areas, beds more than 5 feet thick,

Western Middle field

[table]

A large available supply of coal in the thin beds is indicated, as the thicker beds have been worked more extensively. The United States Coal Commission estimated that there were originaly 4,596,795,000 tons of coal in the Western Middle coal field. Only 13.9 per cent of this amount was in beds less than 5 feet thick, and 42.4 per cent has been developed; whereas of the 86.1 per cent of the total in the thick beds 65.3 per cent has been developed. This record shows that even though the thin beds are not as important in this field, a much greater quantity was taken from the thicker beds than from the thinner beds in proportion to the original amount; therefore a larger proportion of their original coal remains in the thin beds.

Southern field.—Correlative figures for the Southern field appear in Tables 7 and 8.

Table 7.—Thickness, extent, and development of thin beds m SoutJiern field

[table]

Table 8.—Ratios of developed to original areas, beds more than 5 feet thick,

Southern field

[table]

The figures for the Southern field are only approximate, for a sizable reserve in this region has hardly been touched; moreover, very little is known of the deeper beds. Nevertheless, the above figures tonnage in this field may amount to as much as 3,053,000,000 tons, very possibly with a large proportion in the thinner beds.

The tonnage of the thin beds in this reserve area could only be estimated from their ratio to the thick beds in the known area.

Summary.—Tables 9 and 10 summarize the data for the whole anthracite region.

Table 9.—Thickness, extent, and percentage of coal mined from thin beds of

the anthracite field

[table]

Table 10.—Ratios of developed to original areas, beds more than 5 feet thick,

anthracite field

[table]

As has been stated already for the Southern field, the percentages are only approximate, because the reserve tonnage in each of the fields can not be definitely estimated, but they are more nearly correct for the other fields, as the percentage of reserve tonnage to total tonnage is much lower. In the Southern field this percentage is 30.5, in the Northern field 2.7, in the Eastern Middle field 4, and in the Western Middle field 10.1.

The flat measures are of much wider extent in the Northern field than in any of the other fields. The smallest proportion of flat beds is probably in the Southern field.

CORRELATION OF COAL BEDS

In a study like this it is important to know the relation between the beds in different fields; therefore the charts, Figures 1 and 2, have been prepared to show the correlation of the beds. In addition, Figures 3 and 4 cover all four fields, correlating them and showing the different local names of the beds. Unfortunately, a variety of names have been given the same bed, therefore it is almost impossible to determine the beds by name from field to field. Figures 3 and 4 represent attempts to correlate the data. These tonnage in this field may amount to as much as 3,053,000,000 tons, very possibly with a large proportion in the thinner beds.

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The tonnage of the thin beds in this reserve area could only be estimated from their ratio to the thick beds in the known area.

Summary.—Tables 9 and 10 summarize the data for the whole anthracite region.

Table 9.—Thickness, extent, and percentage of coal mined from thm beds of

the anthracite field

[table]

Table 10.—Ratios of developed to original areas, beds more than 5 feet thick,

anthracite field

[table]

As has been stated already for the Southern field, the percentages are only approximate, because the reserve tonnage in each of the fields can not be definitely estimated, but they are more nearly correct for the other fields, as the percentage of reserve tonnage to total tonnage is much lower. In the Southern field this percentage is 30.5, in the Northern field 2.7, in the Eastern Middle field 4, and in the Western Middle field 10.1.

The flat measures are of much wider extent in the Northern field than in any of the other fields. The smallest proportion of flat beds is probably in the Southern field.

CORRELATION OF COAL BEDS

In a study like this it is important to know the relation between the beds in different fields; therefore the charts, Figures 1 and 2, have been prepared to show the correlation of the beds. In addition, Figures 3 and 4 cover all four fields, correlating them and showing the different local names of the beds. Unfortunately, a variety of names have been given the same bed, therefore it is almost impossible to determine the beds by name from field to field. Figures 3 and 4 represent attempts to correlate the data. These

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