Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Viscous circle

I wonder if Mike Keedwell (letters, Ground Engineering, September) sees evidence of 'viscous behaviour' in the ground in this photo taken in a flight along the Grand Canyon 18 months ago? Below the canyon rim are rocks up to 1,000 million years old, formed when palaegic western North America was often inundated with warm shallow equatorial seas. Deep among these rocks there are ancient desert sands, which show fossil tracks of reptiles earlier than the dinosaurs.

Subscribe for full online access and get...

  • Full, instant access to all stories
  • Customised email alerts straight to your inbox
  • Monthly print magazine

Register for guest access to keep reading and get..

  • A free taste of other selected news stories
  • Daily email newsletters


Already have a subscription or ICE membership? or