GEOLOGY AND GEOMORPHOLOGY
East district is a part of the Eastern Himalayas and exhibits identical geological features as in other parts of the Eastern Himalayas.Five geological units encountered in the district are Kanchenjunga gneiss, Darjeeling gneiss, Chungthang schists and gneiss , lingtse granite gneiss and daling group of rocks consisting of Phyllite, Slates, Quartzites and Schist of Pre-Cambrian age. Quartenery deposits of alluvium are sporadically developed along the streams and rivers. Due to different sets of structural disturbance numerous fractures, faults, joints, folds etc. have developed in the rocks occuring in the district. Prominent linaments as displayed by geological formation in the area trend along N-S, E-W, NE-SW, ENE-WSW and NW-SE directions.
In the East District out of the total geographic area (964 sq km) , 679 sq km of area is covered by forest which is 71.17 percent of the total geographic area. Very dense forest occupies162 sq km of the total geographic area, 396 sq km is occupied by the densed forest and 121 sq km is occupied by the open forest. The major physiographic units are hill, valley and slope. The major drainage system in East district are Teesta, Rangpo Chhu and Dik Chhu.