ift ▁Zone ▁( GC R Z ), ▁the ▁northern most ▁portion ▁of ▁the ▁East ▁Pacific ▁R ise . ▁The ▁G CR Z ▁and ▁the ▁San ▁Andreas ▁F ault ▁both ▁terminate ▁near ▁the ▁south ▁end ▁of ▁the ▁Sal ton ▁Sea , ▁in ▁an ▁area ▁called ▁the ▁B raw ley ▁Se ism ic ▁Zone . ▁ ▁The ▁B raw ley ▁se ism ic ▁zone ▁is ▁an ▁active ▁spread ing ▁center ▁that ▁connect s ▁the ▁San ▁Andreas ▁F ault ▁system ▁with ▁the ▁Imperial ▁F ault ▁Zone ▁to ▁the ▁south . ▁ ▁The ▁Sal ton ▁Tr ough ▁is ▁also ▁referred ▁to ▁as ▁a ▁sed iment ary ▁bas in ▁because ▁the ▁bas in ▁has ▁filled ▁with ▁sed iment ary ▁depos its ▁as ▁quickly ▁as ▁the ▁bas in ▁has ▁been ▁s inking . ▁ ▁In ▁some ▁areas , ▁the ▁sed iment ▁is ▁more ▁than ▁ ▁deep . ▁S ources ▁of ▁the ▁sed iment ▁are ▁the ▁mountain ous ▁areas ▁that ▁surr ound ▁the ▁tr ough , ▁and ▁the ▁Colorado ▁River , ▁which ▁in ▁the ▁past ▁fed ▁Lake ▁C ahu illa , ▁a ▁large ▁in land ▁fresh water ▁lake , ▁that ▁disappeared ▁after ▁the ▁Colorado ▁River ▁changed ▁course ▁to ▁the ▁G ulf ▁of ▁California . ▁ ▁Fact s ▁about ▁the ▁Sal ton ▁Tr ough ▁At ▁ ▁below ▁sea ▁level , ▁the ▁Sal ton ▁S ink ▁is ▁the ▁top ographic ▁low ▁area ▁within ▁the ▁Sal ton ▁Tr ough , ▁and ▁is ▁the ▁second - low est ▁point , ▁after ▁Death ▁Valley , ▁on ▁the ▁North ▁American ▁continent . ▁ ▁At ▁ ▁the