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 delta is formed by deposition of sediment at the mouth of a river by water fanning out. 
Fact 2: Erosion is responsible for wearing down exposed places and depositing sediment in level places.
a delta is formed by erosion.

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: Cancer is a disease in which cells divide out of control. 
Fact 2: After lung cancer, the commonest cancers in Britain are cancers of the breast, bowel and prostate.

The most common areas affected by a disease in which cells can divide out of control are lung, breast, and prostate.