Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Fact 1: the surface of a beach is formed by mechanical weathering. 
Fact 2: Beaches and Sand Dunes Dunes are accumulations of sand blown from the beach by the wind.
sand formations are formed by wind.

Fact 1: having food has a positive impact on an organism 's health. 
Fact 2: Animals eat plants for food.
Eating plants has a positive impact on the health of animals.

Fact 1: a mirror is used for reflecting light. 
Fact 2: Typical mirror materials are quartz or nickel plated aluminum.

quartz or nickel plated aluminum are used for reflecting light.