Kolli Hills is a major mountain range and is an outliner of the Eastern Ghats. It is eighteen miles ( 28 Kilometeres) long (north south) twelve miles(19 Kilometers) wide (east/west) and covers approximately 400 square miles. The name Kolli Malai refers to the mountain's once hostile nature; the unsuspecting and unaclamatized aliens, attracted by natural beauty. Viewed from plains of Namakkal the mountain appears as a flat-topped mass. The mountain has been inhabitated from prehistoric times. It is much celebrated in the Tamil Literature of the Sangam period; at least eleven poets mention it in their poems. Next to the Servarayan, this is the only mountain that is still covered with remnants of rain forests.
The government reserve forests are seen in Ariyur, Puliyan Solai, Selur and Vazhavandhi Nadu. An area of 2,00 hectares is in the process of reforestation. Tigers and elephants which were once common in it are now extinct; only small animals such as black bears, hares, porcupines, and wild dogs are seen.
The government reserve forests are seen in Ariyur, Puliyan Solai, Selur and Vazhavandhi Nadu. An area of 2,00 hectares is in the process of reforestation. Tigers and elephants which were once common in it are now extinct; only small animals such as black bears, hares, porcupines, and wild dogs are seen.





