rot.

Found this buried in the dirt in the crawlspace after the living room floor came up.  Think the DMV still has records on this one?

I pulled up the old oak flooring in the living room.  These two perpendicular layers of pine flooring were underneath.  The upper layer was fine but the bottom layer had some serious decay.  Looks like it rotted and someone long ago just covered it up rather than removing it.   I still don't know why  it had water damage - maybe a leaky roof at some point?

These boards in the middle were so rotten that they pulled up easily by hand.

Then I discovered some major rot in framing of the enclosed porch.  Now I know why the left side of the window was sinking.   The floor joist on the left just fell over when I pulled up the last strip of flooring.

The last layer coming up... Before I replace the subfloor I'll put diagonal bracing between the floor joists to add rigidity since they're so widely spaced and add a single pier in front of the fireplace to carry the weight of the future woodstove.   While I'm at it I'll clean all the old bones and trash out of the crawlspace and put down a vapor barrier.  And of course I'll have to rebuild the rotten framing under the window. 

gone.