The Binary Black Hole Alliance was formed to study the collision of bl
ack holes and the resulting gravitational radiation by computationally
solving Einstein's equations for general relativity. The location of
the black hole surface in a head-on collision has been determined in d
etail and is described here. The geometrical features that emerge are
presented along with an analysis and explanation in terms of the space
time curvature inherent in the strongly gravitating black hole region.
This curvature plays a direct, important, and analytically explicable
role in the formation and evolution of the event horizon associated w
ith the surfaces of the black holes.