Tuesday, 19 October 2010

Sedimentary features query

Can anyone identify these please?
Let us know what you think either on 'comments' on this blog or by email.
Please ask if you would like a better image of any of them.


Alan, Canada said...

The two "brown" images could be
(secondary) weathering structures. It looks like secondary iron percolation has hardened the "banding" that has been etched out by ? aeolian action.

David Smith said...

They are iron concentrations (usually hematite or goethite) formed during diagenesis or during other episodes of fluid flow, for example fluid flow associated with fracturing during deformation. They are called Liesegang bands or Liesegang rings.

They are well known by chemists as well: http://en.wikipedia.org/wiki/Liesegang_rings

Earth Learning Idea said...

More suggestions to the same query have been left on http://geologywestcountry.blogspot.com