(ff/Mag; of prefer-ma? Eoe 7%mmtam a. V .4 / _, ,1 u r 1.1V , , ,: . F. 1' a? (g art 15:55 141 ,4 :31?" '- tie/Jere: 1 YL 5' 3 b x I'f/olcanic landforms dominate this landscape. The jagged, lZ-mile long Painted Rock Mountains were thrust up through volcanic rocks and covered with basalt lava ows. north toward the Gila River, spreading the lava in sheets and shallow ponds up to 45 feet thick. - Northwest - Oatman Mountain is made of numerous basalt v. w ' - . . ows, which eventually mounted into the looming landform before you. The southern apron of this mountain consists of several episodes of later lava ows, like those south of the river. A shield volcano visible to the southwest as a low round hill on the at-lying Sentinel Lava Flow is one of the most recent volcanic eruptions. Roughly 3.1 million years ago, lava ows moved steadily A shield volcano" r. .x Lari-mu) allqpvo Illa, an illHlel Kuwait 1 Hill-Jill .wnul on ilrr gmuml I |" .. W. -- lhll i llllll] {ltilHt AIUIHJ ha [1 "w lliijlriULLLI SM V Il',illllllllili?Ill|||llU1'lI.Hl iii-Hl.hllll}l"i J:- caldera /:. lame I :nlml mil mjllilzgilml"; llfi. .I Cullalmeli Lillieh: GEOlogiC Facts About thepetroglyphs The rock knolls here beside you consist of a granite outcrop, overlain by highly weathered basalt boulders. The dark basalt rocks have experienced a long period of weathering. Over thousands of years, desert winds, rain, and alkalines have ' gradually covered these rocks with a dark, hard, shiny coating known as desert varnish. This dark varnish provided an excellent medium for petroglyph artists. When the coating was peeked away, it revealed the lighter color basalt below, making the images stand out. The Web Wheeler-twin