Zeacliff Pond as it looked in July 1959 from the north edge of the pond looking south towards Mt. Carrigain

I took this photo with my Anschomatic camera late in the afternoon from the north shore of the pond and pretty close to where I took the photo above. Two things stand out in the comparison. One is that there is a lot of plant growth on the surface of the pond in this photo. The second is that the pond had considerably more water area than it does now. Most mountain ponds are formed out of glacially carved depressions or from glacially formed eskers, pockets created when chunks of glacial ice melted slowly after the glaciers had receded leaving a hole the size of this pond to fill with water. A pond is a body of water in which sunlight reaches the bottom (as opposed to a lake where the water is too deep for sunlight to reach the bottom). Sunlight, of course, turn green plants into little factories in which photosynthesis makes green plants grow, even aquatic green plants. Photosynthesis uses carbon dioxide (CO2) to make sugars that are stored in the plants and it produces oxygen as a kind of by product that is used by other things like fish. Photosynthesis needs carbon dioxide, CO2, to make the essential sugars for plant growth. CO2 in the pond might come from decaying plant material but too much CO2 would also cause the "death" of the pond. Once the CO2 tipping point is achieved the pond would begin to eutrophy like Zeacliff and some of the other mountain ponds. Another simpler way to think about this is that ponds, including mountain ponds, are 'alive' in a sense. They are like an organism that lives and eventually dies and in the process of living it maintains a kind of status quo scientifically termed 'homeostasis', an equilibrium, but the equilibrium will eventually reach entropy and collapse and the pond will begin a new life and seek out a new equilibrium as a bog, or swamp, or meadow, or forest.