Aestivation Aestivation Aestivation or æstivation (from , summer, but also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. It takes place during times of heat and dryness, the hot dry season, which are often the summer months. Invertebrate and vertebrate animals are known to enter this state to avoid damage from high temperatures and the risk of desiccation. Both terrestrial and aquatic animals undergo aestivation. The fossil record suggests that aestivation may have evolved several hundred
History of the San Fernando Valley the location of human settlements in the San Fernando Valley was constrained by two forces: the necessity of avoiding winter floods and need for year-round water sources to sustain communities through the dry summer and fall months. In winter, torrential downpours over the western-draining watershed of the San Gabriel Mountains entered the northeast Valley through Big Tujunga Canyon, Little Tujunga Canyon, and Pacoima Canyon. These waters spread over the Valley floor in a series of braided washes that was seven miles wide as late as the 1890s, periodically cutting new channels and reusing old ones, before sinking into the gravelly