▁It ▁is ▁named ▁after ▁one ▁of ▁the ▁classical ▁al bed o ▁features ▁on ▁Mars . ▁Its ▁name ▁was ▁officially ▁approved ▁by ▁I AU ▁on ▁ 2 0 ▁March ▁ 2 0 0 7 . ▁It ▁extends ▁from ▁latitude ▁ 7 3 . 7 9 ° N ▁to ▁ 7 7 . 5 ° N ▁and ▁from ▁longitude ▁ 2 9 1 . 3 8 ° E ▁to ▁ 3 0 1 . 4 ° E ▁( 4 3 . 9 8 ° W ▁– ▁ 5 7 . 0 8 ° W ). ▁Its ▁centre ▁is ▁located ▁at ▁latitude ▁ 7 5 . 5 5 ° N , ▁longitude ▁ 2 9 7 . 2 8 E ▁( 6 2 . 7 2 ° W ), ▁and ▁has ▁a ▁diameter ▁of ▁. ▁ ▁Sit on ▁Und ae ▁is ▁part ▁of ▁a ▁cluster ▁of ▁sand - se as ▁( und ae ), ▁which ▁along ▁with ▁Hyper b ore ae , ▁and ▁Ab al os ▁Und ae , ▁overlay ▁the ▁low lands ▁of ▁V ast itas ▁B ore alis . ▁Sit on ▁Und ae ▁super poses ▁the ▁deep est ▁bas in ▁of ▁the ▁northern ▁region ▁of ▁Mars ▁and ▁contains ▁am orph ous ▁sil ica - co ated ▁glass - rich ▁d unes . ▁It ▁is ▁the or ised ▁that ▁the ▁formation ▁of ▁Sit on ▁Und ae ▁may ▁have ▁occurred ▁during ▁early ▁er os ion ▁inc idents ▁of ▁the ▁Plan um ▁B ore um ▁c avi ▁unit , ▁and ▁that ▁R up es ▁Ten uis ▁may