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I <br /> T 1042 146 . <br /> is nowhere exwsed so that 'it is not known. if it is cor'ifarm- <br /> abl.e. Vith the- underlying..rhyo lite tuff., breccia, and,,Cob- <br /> Slomerate uni.t* No. units are observed to overlie -the . <br /> rhyolite breccia. It -is generally very thick-bedded atd <br /> unsorted, and bedding -is difficult .,tc 'r ghize. Figtw 21 <br /> ahowfs a typical. Outcrop on Ben West. mill. <br /> The blocks in the brecciA are felsitic :r2�yctlite� and <br /> pumice averaging 75 ,aua, {approximately 3 wri,th a mixi.mum <br /> of 150 mm in diameter. They decrease Sant size towards the <br /> south where the unit becomes a rather coarse lapil.li-t•,xff. <br /> A further reduction in the size of the lapilli, would maA.e <br /> this unit indistinguishable from the lapi.l,l -tuffs of the <br /> underlying unit. This might explain the apparent ab o::.ae of <br /> this, unit farther south. The breccia is so silicif ' "that <br /> the original ebara.ctef of the matrix- Is dxffi.cglt to deter- <br /> mine. It my have 'keen a. fine tuff, making th6 roo?k a tuff - <br /> breccia. Thin quartz Veizilets and liamoni;te.�stai ni.ng,• in- <br /> tense in places: : eate the 'rock*, Silicification, hap made <br /> .the unit a ver- xesi�stant ridge-foimer. The unsorted and <br /> uattratifi.o character of the. unit tt%,Sests az laharic`,ox°igjn <br /> but its: .'m zw lithi:r: 'ebaracter suggosts that a pyroclaptic <br /> origin is rw re likely. <br /> Ithvte Volcan.ic Sandstones <br /> This-unit .lobal.ly. rests upon the rhyo.lite tuff, brocci.a, <br /> - i <br />