Geography and Geology
Spiti, surrounded by high mountains on all sides, is located on the leeward side of the Trans-Himalayas. Its immediate neighbors are Ladakh, Tibet, Kinnaur & Kullu. The Himalayas are the youngest mountain range on the planet and have a fascinating geological past dating back millions of years. The Spitian Himalayas afford a fascinating insight into the geological past of the Himalayas.
The Spiti river, originating from the foot of a glacial peak marked K-III on old maps, flows approximately160km in a south-easterly direction up to its confluence with the Pare Chu at Sumdo (district border between Spiti and Kinnaur). It goes on to merge into the Satluj at Khab further downstream.
The river has carved out a unique storehouse of Shale. Rock faces in the area are veritable storehouses of the geological history of the Himalayas, dating back to 500 million years. The Spiti valley has an amazing proliferation of Precambrian/Cambrian era fossils. The valleys of the Lingti and the Pin rivers have long been frequented by fossil research scientists. A recent study by the Geological Society of America shows that Spiti houses various unique and rare fossils of marine life (Trilobites, of the Paleozoic Era are some of the earliest legged creatures, relatives of crabs, centipedes and spiders).
Lying in the rain shadow of the mighty Himalayas, Spiti receives scanty rainfall. A cold desert at an average altitude of 4000mts, the valley experiences extremes of climate and temperature variations ranging from -25 degree to +30 degrees centigrade. For more than 4 months of the year the Spiti valley remains obscured by harsh winters.