What's significant about the latest find is that the rocks are the "first ever" discovered on the Red Planet to contain streambed gravels. The rocks were found by Curiosity last fall. Examining them over time, researchers actually were able to determine how deep and fast the water flowed at that location. "At a minimum, the stream was flowing at a speed equivalent to a walking pace -- a meter, or three feet, per second -- and it was ankle-deep to hip-deep," Rebecca Williams of the P