Mining and Geology. The stratum lying immediately above a coal seam, orebody, or other formation; the top of a working or gallery.
| 单词 | θ6288 |
| 释义 | the world > the earth > minerals > mineral deposits > features of stratum or vein > [noun] > material above > above coal (4) roof1575 Mining and Geology. The stratum lying immediately above a coal seam, orebody, or other formation; the top of a working or gallery. wark1707 (See quots.) top rock1803 the uppermost stratum of (hard) rock. wash1882 Mining. ‘A formation of gravel, etc. over an abraded coal-seam’. (Eng. Dial. Dict.) |
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