The Central Himalayas encompasses the areas with the highest topographic relief. The Central Himalayas is again separated into four zones:The High Himalayan Crystalline Sequence (HHCS)The Tethys Himalaya (TH)The Nyimaling-Tso Morari Metamorphic Dome (NTMD)The Lamayuru and Markha Units (LMU)
Dampier-Hodges line is an imaginary line drawn in 1829-1830 to mark the northern boundary of Sundarbans delta. It passes through 24 Parganas South and North districts of West Bengal.