▁of ▁the ▁town ▁of ▁the ▁same ▁name ▁at ▁the ▁eastern ▁border , ▁is ▁an ▁artificial ▁body ▁of ▁ 6 , 0 0 0 ▁square ▁metres . ▁It ▁is ▁known ▁for ▁its ▁fish ing . ▁ ▁Rel ief ▁Most ▁of ▁the ▁Far ▁North ▁lies ▁at ▁a ▁relatively ▁low ▁elev ation . ▁This ▁lower - lying ▁portion ▁makes ▁up ▁part ▁of ▁the ▁Ch ad ▁P lain ▁and ▁s lop es ▁g ently ▁from ▁about ▁ 5 0 0 ▁metres ▁in ▁the ▁south west ▁to ▁ 2 0 0 ▁metres ▁at ▁the ▁Log one ▁River . ▁The ▁average ▁elev ation ▁of ▁this ▁bas in ▁is ▁ 2 8 0 ▁metres . ▁The ▁Diam ar é ▁P lain ▁occup ies ▁the ▁lower ▁third ▁of ▁the ▁Ch ad ▁plain ▁and ▁is ▁character ised ▁by ▁a ▁number ▁of ▁isolated ▁ins el berg s . ▁ ▁The ▁Mand ara ▁Mountains ▁at ▁the ▁south western ▁border ▁with ▁Niger ia ▁form ▁the ▁highest ▁point , ▁lying ▁between ▁ 5 0 0 ▁and ▁ 1 0 0 0 ▁metres , ▁with ▁an ▁average ▁of ▁about ▁ 9 0 0 ▁metres . ▁Mount ▁Tour ou ▁is ▁the ▁highest ▁point , ▁at ▁ 1 , 4 4 2 ▁metres . ▁These ▁mountains ▁likely ▁arose ▁as ▁a ▁result ▁of ▁the ▁same ▁t ect onic ▁activity ▁that ▁gave ▁rise ▁to ▁the ▁B én ou é ▁De pression ▁in ▁the ▁North ▁Province . ▁The ▁area ▁was ▁once ▁vol can ically ▁active , ▁as ▁a ▁number ▁of ▁fre est and ing ▁ne cks ▁of ▁tra chy te ▁and ▁r