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2006 Subsidence and Geologic Flald Observations <br />Box Canyon. West Fla6mn Apache Rocks. and South of Divide Mining Areas <br />during excavation. )luwcvcr, this type of cracking also occurs in soil and a+lluviwn where routs <br />of brush :uui trees arc pulled out of the road cut by the bulldozer. In contrast to suhsrdt:nce <br />crack.. construction cracks occur ut a rather continunu; zone where weathered and: ur tinctured <br />bedrock has been cut through, or where brush :rod trees have been pulled out of .oil andior <br />collu~iutn. <br />y ~~ <br />r <br />9 - <br />h/_ .r- <br />~, ~ ~ ~ fr* <br />1 _ <br />- ~~ ~ l <br />~'.I ~ <br />/ , ' _ ~~ ' <br />_ ~ M, ~ ~ <br />Figure 2 ihi<iut hank ne M~rJn,~k i. lu:,ucd .ibo~¢ mind luge~r atl i+anel t7 in atci+aouu ntxu u! <br />aril aitc Mn«- 17.U=. Cra<k~ un cilhcr .Wc of Jununtvu. imgular crack I riµM nuJdlc! an natural <br />ur the result ,~I cnnstru.!ion. fhc tna:+ pronnnau irrrculur cnrek ha.• an c.unnn.~l 'S txrccm <br />~dch!nvnl of brio} mmc n•lal.tl <br />The most diauiostic diffvrencc between subsidence cracks and umstruction cracks is that the <br />construction cracks I) h<nr a less ragulnr pattern, 2) ore rclatexl to the material they occur in. and <br />~) lack am spatial relationship to the Inngc~all mining gcuntetry. <br />2.3 Desiccation Cracks <br />Desicratiun cracks te7td to occur in clavstoncs and siltstoncs u( the Wcsaccrdc sod 1y':Latch <br />Formations in the 1~bst Elk \dine areal ccherr the rucks arc weathered to clays and silts IFigurc 3). <br />637-tl3'/..750 Wright Waler Engineers, Inc. Page 5 <br />Oecembor2006 <br />