ant ▁is ▁a ▁ ▁high ▁hill ▁in ▁the ▁community ▁of ▁T raw sf yn y dd ▁in ▁the ▁county ▁of ▁G w yn ed d ▁in ▁North ▁Wales . ▁It ▁has ▁a ▁number ▁of ▁western ▁to ps , ▁the ▁highest ▁of ▁which ▁reaches ▁a ▁height ▁of ▁ ▁over looking ▁the ▁water body ▁known ▁as ▁L lyn ▁G elli - G ain ▁and ▁another ▁at ▁Fr î dd ▁W en ▁exceed s ▁. ▁To ▁the ▁south ▁of ▁the ▁lake ▁is ▁the ▁top ▁of ▁P î g ▁Id ris ▁which ▁reaches ▁ 4 2 9 m . ▁The ▁minor ▁top ▁of ▁Y - F o el ▁att ains ▁ 4 3 0 m ▁to ▁the ▁n ortheast ▁of ▁Mo el ▁O ern ant . ▁ ▁Ge ology ▁ ▁The ▁hill ▁is ▁formed ▁largely ▁from ▁the ▁mud st ones , ▁s ilt stone ▁and ▁sand st ones ▁of ▁the ▁Ma ent w rog ▁Form ation ▁and ▁the ▁s ilt st ones ▁of ▁the ▁underlying ▁C log au ▁Form ation , ▁component ▁units ▁of ▁the ▁M aw dd ach ▁Group ▁of ▁Camb rian ▁age ▁sed iment ary ▁rocks . ▁Sand st ones ▁and ▁s ilt st ones ▁of ▁the ▁Gam lan ▁Form ation ▁of ▁the ▁Har le ch ▁Group ▁are ▁also ▁present . ▁An ▁ igne ous ▁intr usion ▁of ▁micro ton al ite ▁lies ▁to ▁the ▁west ▁of ▁the ▁sum mit ▁and ▁the ▁whole ▁hill ▁is ▁cross - cut ▁by ▁dy kes ▁of ▁similar ▁material ▁and ▁later ▁dol er ite . ▁Some ▁quart z ▁ve in