  Global scale impacts modify the physical or thermal state of a substantial
fraction of a target asteroid. Specific effects include accretion, family
formation, reshaping, mixing and layering, shock and frictional heating,
fragmentation, material compaction, dilatation, stripping of mantle and crust,
and seismic degradation. Deciphering the complicated record of global scale
impacts, in asteroids and meteorites, will lead us to understand the original
planet-forming process and its resultant populations, and their evolution in
time as collisions became faster and fewer. We provide a brief overview of
these ideas, and an introduction to models.
