I have been watching "India: natures wonderland."
In today's segment, some annoying mountain dude has been banging on about the Himalayas. Well, at least the mountain scenery has been pleasant.
But then he brought me to a halt: the Himalayas are growing, he noted. (True.) "It's only a few inches a year, but it has been going on for millions of years."
This made my inner engineer get out my calculator. How many is "a few"? Let's say three. And how many "millions of years"? He had mentioned that the Himalayas or 40 million years old a bit earlier… Let's say half that time, just to see where we get.
3 * 20,000,000 = 60,000,000 inches of growth
60,000,000 / 12 inches per foot = 5,000,000 feet of growth
So, the average mountain in the Himalayas is around 5 million feet tall. No wonder people need to carry oxygen when going up Everest!
Apparently the Himalayas are currently growing at a rate of 2 to 3 inches per year. But obviously, that rate hasn't been kept up for even 1 million years, let alone "millions."