Ç or uh ▁River , ▁in ▁the ▁n ort he astern ▁part ▁of ▁Turkey . ▁Out side ▁the ▁valley ▁the ▁top ography ▁is ▁mountain ous , ▁with ▁am ple ▁mountain ▁for ests . ▁The ▁highest ▁hills ▁are ▁Ak da ğ ▁of ▁ 3 , 0 3 0 ▁m ▁and ▁K ı r da ğ ▁of ▁ 2 , 0 0 0 ▁m . ▁Ann ual ▁average ▁temperature ▁is ▁ 1 0 . 2 ° C . ▁ ▁O lt u ▁is ▁famous ▁for ▁its ▁O lt u ▁stone ▁or ▁O lt u ▁gem stone , ▁known ▁as ▁black ▁am ber ▁with ▁d ull - br ight ▁black ▁color ▁and ▁car ved ▁to ▁produce ▁j ew el ry , ▁ros ary ▁be ads , ▁key - ch ains , ▁pip es ▁and ▁boxes . ▁ ▁Notes ▁ ▁External ▁links ▁ ▁O lt u ▁ ▁O lt u ▁News ▁( O lt u ' dan ▁Gün cel ▁Hab er ler ) ▁ ▁O lt u ▁News ▁( O lt u ▁Hab er ▁Portal ı ) ▁ ▁Phot ographic ▁survey ▁and ▁plan ▁of ▁O lt u ▁Castle ▁▁▁ ▁Category : Pop ulated ▁places ▁in ▁Erz ur um ▁Province ▁Category : T ao - K lar jet i ▁Category : D istrict s ▁of ▁Erz ur um ▁Province ▁Category : K ars ▁O blast ▁Category : T own s ▁in ▁Turkey <0x0A> </s> ▁Joseph ine ▁Ober mann ▁( born ▁June ▁ 1 5 , ▁ 1 9 8 3 ▁in ▁R ast att ) ▁is ▁a ▁German