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: a ship is used for moving people across bodies of water. 
Fact 2: Commonly, a bridge is a structure built to cross a body of water.
For short distances, bridges can replace ships.

Fact 1: fossils are formed when layers of sediment cover the remains of organisms over time. 
Fact 2: All streams carry sediment .
Fossils are formed when layers of something streams carry cover the remains of organisms over time.

Fact 1: Marine species live mainly in shallow coastal waters. 
Fact 2: Marine dolphins are endangered by fishing nets, speedboats, and pollution.

dolphins live mainly in shallow coastal waters.