Milk is a mixture of fat, protein, carbohydrate and water. When raw milk sits, the fat separates from the rest of the liquid, rises to the top and forms a layer of cream. The purpose of homogenization is to keep the fat molecules dispersed throughout the milk, so separation does not occur and the milk remains uniform.
In the literature, reported cases of Zone II rupture include the one as described by Naohito et al. [4], of a man falling down stairs resulting in rupture of FDS and FDP. Other cases include one case in the series presented by Naam et al. [2], and 2 cases in the series presented by Imbriglia et al.
That is so interesting that 80906 is now considered in zone 6A. I took a look at a zip code map for Colorado Springs and played with the USDA map site a bit. It says 80906, 80913, 80910, and 80911 are all zone 6A (these are the zones east of you), but then the zone directly south of you is still zone 5B.