Nature documentaries can't be trusted

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."


  1. It's not just nature documentaries. It's everything from reporters. This is a point Michael Crichton made well. Whenever I see a report or article on something I know well the reporter gets it wrong. Sometimes small errors, sometimes a complete mess. But wrong. I bet you have a similar experience. Everyone does. So one,s experience with reporting on topics one knows about teaches one reporting is suspect and not very reliable. But do people generalize this? Most seem not to. "You turn the page, you forget what you know."

  2. Average rate: nearly 0.01 ft/yr (based on your numbers.)

  3. ...oops, 0.01 inches/year.

  4. There's a book about such errors by Paulos, Innumeracy. It's a good book; he lambastes people who don't even try to get the order of magnitude right. After the 2000 election he wrote a piece lamenting Bush's win, and "estimating" the margin of victory. He was off in his calculations, using his data and definitions, by a factor of 3,000,000. I wrote him. He replied "so what? I was making a point."
    I didn't read his later books.


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