▁S tere o ▁Camera ▁( HR SC ) ▁and ▁the ▁Mars ▁Or b iter ▁Camera ▁( MO C ) ▁found ▁that ▁some ▁large ▁dust ▁dev ils ▁on ▁Mars ▁have ▁a ▁diameter ▁of ▁ ▁and ▁last ▁at ▁least ▁ 2 6 ▁minutes . ▁ ▁Y ard angs ▁ ▁Y ard angs ▁are ▁common ▁in ▁some ▁regions ▁on ▁Mars , ▁especially ▁in ▁what ' s ▁called ▁the ▁" Med us ae ▁F oss ae ▁Form ation ." ▁This ▁formation ▁is ▁found ▁in ▁the ▁Amazon is ▁quad rangle ▁and ▁near ▁the ▁equ ator . ▁ ▁They ▁are ▁formed ▁by ▁the ▁action ▁of ▁wind ▁on ▁sand ▁s ized ▁particles ; ▁hence ▁they ▁often ▁point ▁in ▁the ▁direction ▁that ▁the ▁wind s ▁were ▁blow ing ▁when ▁they ▁were ▁formed . ▁Because ▁they ▁exhib it ▁very ▁few ▁impact ▁cr aters ▁they ▁are ▁believed ▁to ▁be ▁relatively ▁young . ▁ ▁, ▁ ▁Pl umes ▁and ▁sp iders ▁At ▁certain ▁times ▁in ▁the ▁Mart ian , ▁dark ▁er u ptions ▁of ▁gas ▁and ▁dust ▁occur . ▁ ▁Wind ▁often ▁blow s ▁the ▁material ▁into ▁a ▁fan ▁or ▁a ▁tail - like ▁shape . ▁ ▁During ▁the ▁winter , ▁much ▁fro st ▁accum ul ates . ▁ ▁It ▁free zes ▁out ▁directly ▁onto ▁the ▁surface ▁of ▁the ▁permanent ▁polar ▁cap , ▁which ▁is ▁made ▁of ▁water ▁ice ▁covered ▁with ▁layers ▁of ▁dust ▁and ▁sand . ▁ ▁The ▁depos it ▁begins ▁as ▁a ▁layer ▁of ▁dust y ▁CO 2 ▁fro st . ▁Over ▁the ▁winter , ▁it ▁rec ry st all izes ▁and