Ecological, Social and Commercial Role of Lichens in India with ...

Acdemia Arena 2010, Supplement 0201
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them was occupied by the great geosynclinals Tethys Sea. The probable date of the commencement
of the elevation of the Himalayas is about the close of the Mesozoic period, but the unveiling of the
story of their structure has only just their begin, and in many cases no dating of the rocks is yet
possible, though they include ancient and relatively recent crystalline intrusive, rocks and
sediments allied to the peninsular part of the India. The section of the range in the district is deeply
cut into by the headwaters of the Alaknanda River, this trunk stream seeming to have reached a
latter stage of development than its tributaries. This much, however is known that there has been
intense metamorphosis. In some part uplift has been considerable since the mid Pleistocene period,
in others there are great stretchers of high but subdued topography and elsewhere there are the
deepest gorges. The direction of folding in these mountain masses is generally North-South. The
geological features of the district from two major divisions which lies North and South of an
imaginary line extending East-South-East between the villages of Helang in Joshimath and
Loharkhet in the Adjoining district in Pithoragarh. The Northern division, which is occupied by
higher range and snow covered peaks consist entirely of medium to high grade metamorphic rocks
and is intruded by later volcanic rocks. The division of the South, occupied by ranges of lower
altitude, consists essentially of sedimentary and low grade metamorphic rock also intruded by later
volcanic rocks. Geologically very little is known of the first division which consists of rocks such
as quartzite’s, marbles and various types of micaceous schist’s and gneisses which a few sporadic
occurrences of garnet, graphite, iron, knit mica and vein quartz. The division of the South of the
imaginary line is better known geologically and consists of rocks such as gneisses, limestone,
phyllites, quartzite, Seri cite biotic chests and slates.
Soils in the region are the coarse soils, well drained and acidic with pH levels varying
between 4 to 5.5 (Sundriyal 1992).
Climate
As the elevation of the district ranges from 800mts to 8000 mts above sea level the climate
of the region very largely depend on altitude. The winter season is from about mid November to
March. As most of the region is situated on the Southern slopes of the outer Himalayas, monsoon
currents can enter through the valley, the rainfall being heaviest in the monsoon form June to
September.
Rainfall
Most of the rainfall occurs during the period June to September when 70 to 80 percent of
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