4 May 2010

Hackles, ribs, plumes

Posted by Callan Bentley

Today, you get a photo from GMU structure student Nik D. This is a small exposure in the Hampshire Formation (Devonian) on New Route 55 in West Virginia. It shows a fine example of plumose structure with the not-often-seen concentric ribs running perpendicular to the ‘plumes.’ At the edge of the joint, you can see the flaring fringe of hackles. Top edge of a Rite-In-The-Rain field notebook for scale:ribs_plumose

Where shall we zoom in? How about these two boxes?ribs_plumose4

Close-up of the concentric ribs:ribs_plumose2

Close-up of the hackle fringe on the edge of the joint:ribs_plumose3

…Even the hackles have hackles!

Good stuff: I love me some fine plumose structure!