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POWDERHORN COAL COMPAPIY <br />o - -- -.... - - - ... -- -- <br />o ---- --- --- --- - - - -~.._ - - ---- - - <br />o - - -- -- _- -- - -:- - .. - ------- ---- - - <br /> <br /> <br />o - ----- --._ ... - --- - - - - -- - - <br />$~.bsidence ~' <br /> • r ` O. 5 <br />p ___.__ - - - --- -------- -- - .. -- - -- - D <br />L <br /> ^„ <br />' %- <br /> ~ <br />I R' Extrac <br />0 '-- -~- - -- --~- ~----_ - ~------ - w' P~~ra r <br /> -- <br />0 /A DD 0 O DO Lb S Mn ~ mn n nn Anm 4nnn <br /> <br /> <br />1-L I _-1: l =-I <br />_ ~ ~~ <br />i) - - Sl. Oft //. 9S ,1.. L.,.. ~N/w~ n <br />z <br />~ 9 Sy. - Q. 78% c <br />m <br />R UD • D eplh ~f/~)/ / <br />lion ~ i1 - I~i nin9 /i~t9~l(f~l <br />6/i doh (f!) -- - <br /> <br />Lmar ~N~l,/) .. <br />Subsidence above room-and-pillar partial extraction workings following <br />pillar squeeze or failure. <br />John F. Abel, Jr. (1982) <br />