Tufa, a type of calcium carbonate deposit that develops in waterbodies, formed within Lake Manix. Based on information gleaned from fossil ostracods, Lake Manix was a well mixed lake, especially in summer; likely, no thermocline developed in it. While the lake may have been warm during oxygen isotope stage 12 and possibly nourished from early summer runoff, after that point it was much colder, with water temperatures not rising above . After oxygen isotope stage 5, the lake became warmer again. The environment of Lake Manix has been compared to shallow lakes in northern California that lie behind the Cascade Range.