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145 <br /> y <br /> moderately welded. A �j.Ar age determination.was- mado on a <br /> :s specirnei of- this tu.f f, but, as stated on p. 20,9 it is, probes <br /> ably unreliable'beoause of cDntamination by' Frecat bri.en <br /> Y <br /> 04s.ement~ <br /> A lightgra�' lalli tuff �lapi.i'li sto crops, aGut, an- <br /> the north -and east dopes of Round lbusitain (Stk-, T. 22 5,.4 <br /> R. 72 W.), , The jiuMi.ce l:apilli, average 'S mm and reach a. max» <br /> i=m of 54 ran in diameter. Some fragments of flow-layered <br /> and fel.si ti.c rhyol.i.te,- and i'recambrian rods also trCCur* <br /> Quartz and vi.tri.c tuff comprise the matrix. on. the south <br /> side o-f' Round %bunta.in 'there occurs *, local area of. tuff» <br /> a4 ' <br /> broccia with blocks of rhyoii.te and Precambrian rocks up to. <br /> a,"diameter of 'WO feet. . ,Both the lapilli-tuff grid the tuff- <br /> breccia are bel.i,4ved to be at a higher stratigraphi,c,hori,on <br /> than the .as lt-f low tuff.. <br /> The bads of tha entire rhy0lite tuff, brecci.a, and con - <br /> fi glomerate unit are mainly epiclast:ic, mostly fluvial, and <br /> laharic, .vi.th" some pri ry and-xe+vrked ,pyroclastic depo�jts. <br /> This is a thin,, tocal unit exposed oily III skt sec.. 3, <br /> az 4 N!li sect, 'S, ' T. 22 so , R. .72 V. vmPre. it ce-Dsa Seri Most <br /> Hill and the zua:rounding ridge~ to the north.a.nd east (Trb <br /> on - plEa.te 3);, It is apprQxi mately 80 feet thick on lien West <br /> lii.l.l, but it, t:hL%, to the, QtrUtn and easti Its lower +cgntac,t <br />