9 April 2011

Plaster joint

Posted by Callan Bentley

Here’s a joint extracted from gelatin during this year’s GMU structural geology “Make a Joint” exercise:

A soda bottle full of congealed gelatin serves a “rock.” We then use construction clamps to impart a stress field to the gelatin bottle. Into it, we inject fluid plaster of Paris. The extra pore fluid pressure causes a joint to form, displaying all the characteristic anatomy. Here’s the other side:

Here are some links to other joints that show similar features (plumose structure, hackle fringes, overall elliptical shapes).