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<br /> <br />Rockfall <br /> <br />RllCKFALL 15 the failing of a newly detached mass of rock from <br />a cliff or down a very steep slope. ~OCk5 In a rockfall can <br />be of any d' mens i on ~ from the size of baseba II 5 to houses. <br /> <br />Characteristics <br /> <br />Rockfalls are the fastest type of landslide and occur most <br />frequently in mountains or other steep areas during early <br />spring when there is abundant moisture and repeated freezing <br />and thaw I n9. The rocks may freefa II or carom down I n an <br />erratic sequence of tumbling. roiling and sliding. When a <br />large number of rocks plummet downward at high velocity, it <br />Is eal led a rock avalanche. <br /> <br /> <br /> <br />"--. ";;.-"'" <br />'" -.' - -..- '. <br />t-'--~ ~ ~ "fO .~ <br />-"~\.:........--$---' '.~ <br />~ - - 'i\-' +- :$&. '" <br />-OJ'-=--.,,~ 4-~;.. <br />r-t ~~. -=-:-.: ~" <br /> <br />_. - :.Q -.' t -.',...."''^ <br />- , "'-""." <br />-- -Mr- '1I-A ::.0...: <br />- -~-..>:1';.."'t. <br />. . ........._ ,.....~..:..~.:J<.:'"'tt..~:~. <br /> <br /> <br /> <br />..... .. <br /> <br />Scenic western settings often are subject to rockfalls and landslides. Here, a <br />weak, erodible rock such a.s shale forms the slope below the sandstone or <br />volcanic caprock. As the shale erodes from beneath, the caprock is a continuing <br />source of rockfall as detached blocks topp Ie and roll down the slope. <br /> <br />30 <br />