I was perusing Anil's archives, and came across this post:

http://anildash.com/2001/09/terry-wallace-a.html

Sadly, the hyperlinked findings in his blog post were 404'ing but luckily were previously archived. Enjoy.

For more about Terry Wallace:

http://web.archive.org/web/20021202032952/http://www.geo.ari...

https://en.wikipedia.org/wiki/Terry_Wallace_(geophysicist)