What does the principle of uniformitarianism tell us about the past?

The definition of the Principle of Uniformitarianism is the assumption that the same natural laws that currently operate in the universe have operated in the universe in the past. These principles apply everywhere in the universe. The Principle of Uniformitarianism has been a key principle in virtually all fields of science. It was proposed in contrast to catastrophism by British naturalists in the late 1700s. It is also the first principle of science. It, therefore, cannot be verified or falsified using scientific analysis. 

The open ocean begins at the low-tide mark and extends to the end of the continental shelf

above statement is not a true statement about the open ocean because the open ocean has low levels of nutrients. most of the photosynthetic activity on earth occurs in the open ocean within the photic zone. organisms in the deep ocean are exposed to frigid temperatures and total darkness but it does not begin at the low-tide mark.