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.
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Question: Fact 1: Earth 's magnetic patterns are used for finding locations by animals that migrate. 
Fact 2: Spring and fall migrations of birds and fish animate the landscape.

Answer: Earth's magnetic patterns are used for finding locations of birds and fish.


Question: Fact 1: erosion causes a river to become deeper and wider. 
Fact 2: Erosion alters the constituents carried by water.

Answer: Deeper and wider rivers alter the constituents carried by water.


Question: Fact 1: igneous rocks are formed from magma cooling. 
Fact 2: When the magma cools and hardens, it turns into igneous rock.

Answer:
magma turns into igneous rocks.