THE discovery of rocks in Nepal that are nearly 10 times as old as the Himalayas themselves suggests that today’s mountains formed on the site of a much more ancient mountain range.
The present-day mountains started to form 55 million years ago when India collided with Asia. But when George Gehrels at the University of Arizona in Tucson analysed rocks from the Himalayas in Nepal, he found that a significant proportion were ancient metamorphic rocks, dating back 500 million years (GSA Today, vol 13, issue 9, p 4). Metamorphic rocks need high temperatures and pressures to form and are often…
