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<br />
<br />The h(nbile Prewix Quarry lies iu ur ,,ear Jackson c;ulci,. The iiii ~+e is
<br />abuur_ 7 miles due nnntf, oC .:ol,lau, Uolora,lu and iiamediately •••est oC U. S.
<br />Route 40, see Ei••ure 1, ~i~,e le„al descripCion of the lucatLon i.^, tu••ns;cip
<br />4S, range 70'd, section L,. 'Pl,e mine is u.. the easC E1auk uE Che Ennt hills
<br />and the elevation changes abr,ipcly to the •.~est. '1'I,e elevation on the east
<br />side of the property is about '700 Le~.t, and rises over a I,ori~outal disC-
<br />ance oC 7000 feet to an elevation of G~00 E.eet I:o I:he ..est. The uiiuc
<br />has been deveLuped on this hill silo and consists of Chree levels, call.:d
<br />in this report the upper, inirldle and lo~.~er levels. Each level hes an ex-
<br />cavation Erom about 50- to 1;0-feet high.
<br />Tl,e mine lies on a north-south Creudiu;; Eau1C Chat separates ti,e se;l-
<br />iments to the east Erom the Foliated u,eCamorphic rucks to the nee C. Jackson
<br />Mulch lies in a nearly east-west Fault that di s about 80-degrees to the
<br />ie nortrern .^sCCe of tl,e fault zone is the do~~m-thro+m sr~ The
<br />lily zone o the fa~lt is about ~ eet ••ide near the top o tie quarry and
<br />ou ~eet +,+i~a near ,e as o .,e m e s repcrte~iat
<br />the U. S, L. S, paper "L`e.l-rockc ~eol u~y oC the Morrison Quadt'angle" sCaces
<br />that the Fault disappears a si,ort distance to the „est of the mine.
<br />The rocks in the quarr;• are a ~nei.ss; rock to Che north side "` the
<br />fault is a dark gray hon,blende ~•neiss ~,it:, small dikes uf: ~~~i.;;atic ~ne,iss.
<br />T'he hornblende ;;ueiss nccrrs in la•'er.^, ti,at are folded iu au anticlinal and
<br />synclinal structure, forming ••avy la•~ers of varyiuL thickness. The rock ou
<br />the south side of C:,e fault is gray-oran,;e, fine-to-course ~raineJ ;~,+,eiss.
<br />1'6is rock is less foliated o••iu~ to intensive mi~~mal:ization and intrusions
<br />of graniCic material.
<br />Photo,•raplcs nC the erpused Faces of the q,:arry and near-by roa.l c~~l s
<br />(3/',ths oL a mile to the south) are preseuC.ud i„ Ei~~,res 2 Clu'oug-:~ 10, '1'!,e
<br />diECurent colors a+,.I Cu1.iaCiuu are clear l" sho•a, Cn the phnto;;ran,s. 'ibe
<br />Em.,lt is sho^^ in Ei• ore i; ~•rl diCEerencos in i'uliaCinn on each side ni Cbe
<br />Eanlt are sL,c•m in Ei.~+,res and ;. The synclinal and anticlinal foliation
<br />is evident in Fi~++res 5, 7, 3 and 9. The diLFerent gneiss is idcitiCied by
<br />color charateristics slto•m in all pr;nts.
<br />'fhe rock is hard and strong +•itl, the exception of the +.+caClnared and
<br />decomposed material near the nu~listnrbed surface. 'Phe unEracutured, uu-_
<br />~•eathered rock is estimated to ~~ave compressive strengc,s o' the order of
<br />G?OLO~~IL" STI:UC'1'URG
<br />fhe geologic structure ~•as visually observed in the upper, n:iddli• aad
<br />lu••er ben=i,es, aa,l n,uas~~rewe~,ts oL I:ur st.ilce and dip „ere ,~,ade •~ith Che aid
<br />of a L•tunCOU Compass. Oaly t.+e iuajur sCr~icCures ••ere recorded, that .s, Che
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