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.

Example Input: Fact 1: rocks interacting with wind over long periods of time causes weathering. 
Fact 2: Rock weathering and erosion produces a continuous stream of sediments that are laid down in layers.
Example Output: rocks interacting with wind produces sediments.

Example Input: Fact 1: a vehicle is used for transportation. 
Fact 2: Cars are vehicles and trucks are vehicles.
Example Output: A car is used for transportation.

Example Input: Fact 1: natural magnetism is used for pointing north by a compass. 
Fact 2: For the ordinary compass, align to the North direction.
Example Output:
compasses use magnetism.