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: soil is formed by weathering. 
Fact 2: Soils are formed by breakdown of rock.
Weathering is the breakdown of rock.

Fact 1: Earth 's tilt on its rotating axis causes seasons to change. 
Fact 2: Habitats change with the seasons.
Earth 's tilt on its axis causes habitats to change.

Fact 1: a polar bear requires a cold environment. 
Fact 2: Cold environments usually mean lower numbers of animals, both predator and prey.

polar bears live where there are fewer animals.