▁the ▁rest ▁of ▁the ▁region . ▁Some ▁ped est als ▁have ▁been ▁accur ately ▁measured ▁to ▁be ▁hundreds ▁of ▁meters ▁above ▁the ▁surrounding ▁area . ▁This ▁means ▁that ▁hundreds ▁of ▁meters ▁of ▁material ▁were ▁er oded ▁away . ▁The ▁result ▁is ▁that ▁both ▁the ▁cr ater ▁and ▁its ▁e ject a ▁blank et ▁stand ▁above ▁the ▁surr ound ings . ▁Ped est al ▁cr aters ▁were ▁first ▁observed ▁during ▁the ▁Mar iner ▁miss ions . ▁ ▁Ring ▁m old ▁cr aters ▁ ▁Ring ▁m old ▁cr aters ▁are ▁believed ▁to ▁be ▁formed ▁from ▁astero id ▁impact s ▁into ▁ground ▁that ▁has ▁an ▁underlying ▁layer ▁of ▁ice . ▁ ▁The ▁impact ▁produces ▁an ▁re bound ▁of ▁the ▁ice ▁layer ▁to ▁form ▁a ▁" ring - m old " ▁shape . ▁ ▁, ▁ ▁H alo ▁C rat ers ▁ ▁B ould ers ▁ ▁D ust ▁devil ▁tracks ▁ ▁D ust ▁devil ▁tracks ▁can ▁be ▁very ▁pretty . ▁ ▁They ▁are ▁caused ▁by ▁giant ▁dust ▁dev ils ▁removing ▁bright ▁colored ▁dust ▁from ▁the ▁Mart ian ▁surface ; ▁thereby ▁expos ing ▁a ▁dark ▁layer . ▁ ▁D ust ▁dev ils ▁on ▁Mars ▁have ▁been ▁photograph ed ▁both ▁from ▁the ▁ground ▁and ▁high ▁overhead ▁from ▁orbit . ▁They ▁have ▁even ▁blow n ▁dust ▁off ▁the ▁solar ▁pan els ▁of ▁two ▁Ro vers ▁on ▁Mars , ▁thereby ▁greatly ▁extending ▁their ▁useful ▁lifetime . ▁The ▁pattern ▁of ▁the ▁tracks ▁has ▁been ▁shown ▁to ▁change ▁every ▁few ▁months . ▁ ▁A ▁study ▁that ▁combined ▁data ▁from ▁the ▁High ▁Resol ution