Processed to 3344 feet, a partially filled fracture

Today we processed rock core to a depth of 3344 ft, 113 ft deeper than yesterday.  Processing was difficult because of how fractured the rocks were, some was too fractured to piece back together.  Below is an example of one of those fractures, but this one is more interesting than most:

This is a nearly vertical fracture that splits the core into two halves (one can see clear through the fracture in person, but the camera couldn't capture any light coming through the back side of the fracture).  Such features aren't rare, but this one is different because its top and bottom ends have been filled by clay and other weathering products.  We often see fractures that are open and others that have been filled, but this one shows both!  A partially open, partially filled fracture that you can literally see through is a unique sight so far for this project.  This feature supports my interpretation that fractures are commonly "healed" by groundwater flow and deposition of sediment through them.  Later compaction by subsequent flows and cementation by further alteration can make fractured rock more solid for our drilling.