While admittedly a bit juvenile, Frozen Marsh Farts is actually a reasonably accurate description of the ice bubble formations shown in the image above. The formations which look like pancakes stacked atop one another are actually bubbles of methane which were encapsulated by ice as the water froze. In shallow bodies of water like a marsh, organic material from dead plants and fish form a layer of decaying organic matter on the bottom. As this organic material decays, it emits methane gas which usually simply bubbles up to the surface and is released into the atmosphere. However when the temperature suddenly drops below freezing, the water will freeze from the top down. A bubble of methane gas released from the bottom can then become trapped underneath the ice layer as the water freezes around it. If another bubble of methane is released from the same spot on the bottom of the marsh, it can rise up until it comes into contact with the bottom of the now frozen, or mostly frozen, bubble where it becomes trapped and eventually frozen in place as well. This process only happens when the rate of the freezing of the water is balanced just right against the interval between methane bubble releases which does not happen often, making this particular phenomena very uncommon in this area.
Methane is one of the gasses which can be present in flatulence, and so bubbles of methane frozen in the water made me think of… well I think you get the idea.
The next two photos are from a different part of the trail, but they nicely highlight the cool patterns of crystal formation that appear in thin sheets of ice.
