1995-96 - Birbal Sahni Institute of Palaeobotany

1995-96
indicate existence of tropical forest all along the Himalayan foot-hills during the deposition
of Siwalik sediments. In one of the studies the presence of zygospores referable to
Zygnemataceae algae was recorded from Siwalik sediments of western Nepal. This evidences
for the clear. stagnant and shallow freshwater environment during the deposition of these
sediments.
Detailed Scanning Elcctron Microscopy was carried out on fossil Selerosperma cf.
S. manii to ascertain the nature of aperture and affinities in fossil and extant pollen. The
existence of African Palm-like plants in the Neyvcli was ·confinned. Scanning Electron
Microscopic studies on the fossil woods from Deccan Intertrappeans and modem charcoal
revealed absence of middle lamella. This suggests that the volcanic erruptions caused fire
which produced fusain at the cost of middle lamella.
On the basis of leaf-impressions from west and central Nepal, a phytogeographical
link between Indian subcontinent and southeast Asia was deduced during Miocene-Pliocene.
Studies were also carried out to understand the fossil flora of northeastern India
during Tertiary Period. The fossil leaves, fruits, seeds and spores and pollen were investigated
to estimate the vegetational components; the palaeoecology of the basin was also assessed.
The fossils of monocotyledonous taxon Nipa. recorded from Makum Coalfield, indicate
that the deposition of coal and associated sediments occurred in coastal environment. In
one of the studies the palynological composition from Namdrik River Section, Changlang
District, Arunachal Pradesh indicated the existence of a humid tropical to subtropical climate
with high rainfall. A shallow marine environment of deposition and subtropical to tropical
climate was interpreted for Tertiary sediments in Garo Hills, Meghalaya.
The Quaternary sediments from south Indian tropical montane forest, Garhwal
Himalaya, Mahanadi Delta and Andaman and Nicobar Islands were palynologically analysed
to understand the history of vegetation and climate. The palynological studies on Spiti Valley
material have revealed cold and dry c1innateduring 2000 to 1500 yrs B.P., while between
1500 to 900 yrs B.P. amelioration in climate is indicated. Thereafter, recurrence of the cold
and dry climate is recorded. The palynological studies from Sadanandpur profile (Malmnadi
Delta) have shown several cyclic changes in the marine transgressive and regressive facies.
On the basis of palynostratigraphy and lithostratigraphy from Sadanandpur the ancient shore
lines have been deduced. The results of palynological studies from a profile dated back to
20,000 yrs B.P. from Andaman and icobar Islands have shown vegetational development in
three phases.
The tree ring chronology is being worked out at the Institute. The results of tree ring
studies of teak from the Wood Museul11of Institute of Wood Science and Technology, Bangalore,
date the wood to the period 1159-1959 AD. In a similar study on a Mesozoic wood­
Podocarpoxylon rajmahalense, wann temperate climate was interpreted for the period.
Phytoplankton
stratigraphy
The phytoplankton studies were continued on marine sediments of Kutch and
Saurashtra, Meghalaya. East Coast and Andaman and Nicobar Islands. The taxonomical
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