Complex sentence: Another form of anchor ice may be observed at the mouths of Arctic rivers where fresh water seeps out of the river bed into the ocean up through the sediment where anchor ice forms if the seawater is below the freezing point of the river water.
Split into simpler sentences: Another form of anchor ice may be observed at the mouths of Arctic rivers where fresh water seeps out of the river bed into the ocean up through the sediment. Anchor ice forms if the seawater is below the freezing point of the river water.