There are two things that cause ocean water to become denser, and those are b) the salinity of water and low temperatures.
The more salt there is, the denser the water will be - take the lake Dead Sea in Israel, Jordan, and Palestine for example.
And the lower the temperature, again, the denser the water will be - the deeper you go into an ocean, it will be more difficult to move around due to density and other things.
Answer: Geology played a major role in Darwin's life and scientific work: The formation of volcanoes, the slow subsidence of coral reefs, the rising of the Andes by earthquakes, the fossil relatives to modern species in South America,
Explanation:
Plant cells have what is perhaps the most complex outer coverings. Plant cell walls are made largely of cellulose which forms strong, highly rigid, almost indigestible coverings that protect the cell and gives it shape.