The rocks of core area mostly, belong to the eastern ghat group of Archean age. The main rocks are gneiss, quartz schist, Khandalite, Charnokites and Granite. Towards Tulka and Raigoda lying east of the Tiger Reserve, Ferruginous quartz, Mica schist occur with Quartzite gneiss, Granite Gneiss which extends up to Katrang. In Raigoda, Bolong and Jocub area, Khondalite is commonly met with, yielding very good quality of sandy loam and it is usually associated with pure sal crop, some times found on hill top, as in Jocub.

Kankar formation of Nodular limestone, which produces heavy impermeable clay are seen in Majhipara, Tikarpara, and Katrang and in the northwestern areas of Bhagmunda blocks. Alluvial soil of lesser extent is met with on the banks of nalas and rivers. The bulk of precipitation occurs during the rainy season through south-west monsoon. Usually monsoon breaks in the third week of June and continues up to middle or end of September. Pre-monsoon showers are also experienced in first or second week of June, but not very common. Post monsoon showers are also experienced in month of October and November. Thunder storm usually occurs during April and May. The average number of rainy days in a year is 100 out of which, 70 are confined to the period between June to September. The annual average rainfall varies from 1250 mm to 1700 mm. The landscape is hilly with moderate to steep slopes. The general elevation is around 350 meters from sea level. The lowest point is 37 mtr above MSL on the bank of river Mahanadi in Katrang RF and the two highest peaks are Sunakhania at 932 mtr in Padmatola Reserve Forest and 842 mtr in Jocub Reserve Forest.

The extensive forests of Pampasar and Purunakote Ranges, comprises of vast tracts of high hills, steep to very steep slopes and deep valleys extending from Athmallik in west to Narsinghpur and Hindol to the east. The ranges of hills lie approximately parallel to Mahanadi valley having a south-east to north-west strike. The slopes of the hills on the east of the Tiger reserve covering Jocub, Bolong, Tulka and Raigoda are very steep and occasionally precipitous. The western part spread over areas like Baghmunda and Majhipara are more moderate.