Temperature-density relationship Water has the maximum density at 4C That's why ice floats on the water surface, reducing heat loss from the water under the ice If water trapped in cracks in rocks freezes the force of expansion would split the rock, an important process in the weathering of rockTemperature-density relationship • Water has the maximum density at 4oC • That’s why ice floats on the water surface, reducing heat loss from the water under the ice. • If water trapped in cracks in rocks freezes, the force of expansion would split the rock, an important process in the weathering of rock