On 2015-05-20 6:52 PM, Greg Young Morris wrote:
> I'd be curious to know how they determine that they're tools and not just
> rocks. To the untrained observer, they look pretty similar to a lot of
> other rocks I've seen

Where the sawdust and shavings fall helps us determine how you work, 
right? It's in the chips, the flakes, the crushing at places where the 
'hammer' came down on the raw material, the type of rock, and the 
distribution of the flakes .

Here's a brief video! 
http://humanorigins.si.edu/resources/multimedia/videos/how-tell-rock-
stone-tool">http://humanorigins.si.edu/resources/multimedia/videos/how-tell-
rock-stone-tool

Google is sometimes your friend.
Don