Jay and Medford, this question is for you ... but I am writing it as a blog post, since maybe other people have come across this, and have some tips.
Subject property is a 1903 "Builder's Craftsman" (In this part of L.A. that means "Poor Man's Craftsman", since the architecture mimics the general Craftsman appearance but lacks the fine (and costly) detail work).
Anyway, the carpeting has been removed, and we discovered that a rather thick layer of putty (I think it's putty) had been applied to the entire surface of the floor.

This was probably done in the 1970s, maybe, to prevent the floor from squeaking under a brand new shag carpet.
So how would you guys approach this?
1. Just leave it be until the professionals arrive with a floor sander?
2. Chip, chisel and scrape it by hand? It does chip off easily in some areas - in other areas not.
3. Run a hand-held belt sander lightly over it?
4. Dampen it a tad first? Then scrape?
I realize no matter what approach, the final result will not be a "perfect" floor. And it this particular house, the "distressed floor" look will be just fine.
And gentle readers, please take this advice. Do not give in to the temptation to putty your floors.