▁Mar iner is ▁ch asm ata ▁( part icular ly , ▁I us ▁Ch asma , ▁Mel as ▁Ch asma , ▁and ▁Cop r ates ▁Ch asma , ▁from ▁north west ▁to ▁n ortheast ). ▁Old er ▁No ach ian ▁bas ement ▁cr ust , ▁likely ▁pred ating ▁the ▁formation ▁of ▁Th ars is , ▁bound ▁the ▁Th aum asia ▁Pl ate au ▁to ▁the ▁west ▁( C lar itas ▁R ise ▁and ▁the ▁Clar itas ▁F oss ae ), ▁the ▁south ▁( Th aum asia ▁high lands ), ▁and ▁the ▁east ▁( C op r ates ▁R ise ▁and ▁the ▁N ect aris ▁F oss ae ). ▁The ▁plate au ▁st ret ches ▁over ▁ 2 9 0 0   km ▁across ▁the ▁surface ▁of ▁Mars ▁and ▁s its ▁at ▁around ▁a ▁ 4   km ▁relief ▁relative ▁to ▁the ▁southern ▁high land ▁terra ins ▁immediately ▁surrounding ▁the ▁Th ars is ▁R ise . ▁ ▁There ▁are ▁two ▁general ▁provinces ▁compos ing ▁the ▁Th aum asia ▁Pl ate au . ▁The ▁north western ▁section ▁of ▁the ▁plate au ▁is ▁composed ▁of ▁high ▁pla ins ▁of ▁Sy ria ▁Plan um , ▁Sol is ▁Plan um , ▁and ▁S ina i ▁Plan um . ▁Th aum asia ▁Plan um ▁forms ▁a ▁lower ▁elev ation ▁region ▁in ▁the ▁east , ▁ab ut ting ▁the ▁Cop r ates ▁R ise . ▁ ▁In ▁general , ▁the ▁plate au ' s ▁highest ▁elev ation ▁rest s ▁in ▁its ▁north west ▁corner , ▁closest ▁to ▁its ▁h inge