Cenozoic plant fossils and the Himalayan orogeny

Abstract

Selected palyno- and megafloras from the Cenozoic Era of extrapeninsular India have been examined in the orogenic context of the Himalaya. Distribution of vegetations and variation in climates are in conformity with the periodic phases of the Himalayan uplift. Continued rise of the Himalaya acted as a barrier for the flow of moisture resulting in lesser precipitation, higher snow cover and increased aridity. In response to the topographical and climatic variations a progressive change occurred in the composition of vegetations during the past 60 Ma. The ancestral tropical floras inhabited the lower slopes, whereas the temperate floras colonized the higher slopes. Altitudinal segregation of floras is clearly evident from the Mid-Miocene orogeny. Palaeocene to Mid-Pleistocene plant diversity generally varies from evergreen, semi-evergreen, dry/moist deciduous, warm temperate to temperate forest types. Migrations/immigrations and extinctions of plant taxa were largely influenced by physiographical and climatic changes. Enrichment and diversification of the Neogene Himalayan floras have also been brought in through the process of evolution. Cult-historical evidences point out that the Himalayan range continued to rise even after the advent of man.