Hiked around on an escarpment overlooking a small valley and a trail around a lake the other day. The lake I got to see is classified as a meromictic lake, which is a somewhat rare type of lake. Due to their incredible depth they are separated into 3 distinct layers usually with the bottom most layer being almost entirely anaerobic, which is really only suitable for the purple sulphur bacteria that dwell there. The lake has no seasonal turnover, so none of the layers ever gets mixed, meaning there's little disturbance aside from the microbes that live there, and organic material that falls into the depths. This means that whatever falls in and settles there, stays there, which has played an important role in determining the geologic history of the area. In the case of this lake, grains of corn pollen were observed in a core sample of the lake bed at around the 1600's mark, which indicated the presence of an indigenous settlement in the area at the time. This led to a further investigation in the surrounding area and they were able to find various tools, weapons, pottery, etc.
