New Delhi, Sept. 4 -- The Indian and Eurasian plates collided about 65 million years ago to begin the process that ultimately formed the Himalaya, and today, the Indian plate continues to plough into Tibet at roughly 4-5cm a year (that is about the speed at which a human fingernail grows). So, if there's one word that describes the Himalaya best, it is "friable". As the youngest and most geologically active mountain range in the world, it is also one of the crumbliest.

While the Himalaya are still growing in height, the range is simultaneously eroding at an average rate of about 2.7mm per year, with the eastern part eroding at a higher rate than the western. A combination of strong monsoon rains and steep-sided valleys are the main reaso...