28 March 2017

P-sol in a conglomerate countertop slab

Posted by Callan Bentley

Over the weekend, I saw this polished slab of countertop outside a hardware store in Berryville, Virginia. I stopped to check it out. What a beautiful conglomerate!

I noticed that many of the cobbles had pronounced weathering rinds:

Here’s another example:

Note the weird shapes of the grains around it – these embayed and flush grain boundaries are intriguing (yellow highlights):

These grain boundaries are indications that pressure solution has taken place in this rock.

They suggest this conglomerate was squeezed a bit, triggering pressure solution of certain minerals. Rocks rich in those minerals (probably quartz in this case) deformed  with their most-highly-pressurized portions dissolving away (changing the shape of the cobble) as less soluble rocks pushed into them.

Explore the whole thing here:


Link 0.85 Gpx handheld GigaPan by Callan Bentley