instruction:
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.
question:
Fact 1: a glacier causes mechanical weathering. 
Fact 2: Mechanical weathering produces detritus.
answer:
A glacier can produce detritus.


question:
Fact 1: a warm front causes cloudy and rainy weather. 
Fact 2: If warm air is advancing on cold air, the front is designated a warm front.
answer:
Warm air advancing on cold air can lead to cloudy and rainy weather.


question:
Fact 1: Osteoporosis is a disease in which osteoclasts are more active than osteoblasts. 
Fact 2: Bone density decreases with osteoporosis.
answer:

A disease in which osteoclasts are more active than osteoblasts decreases bone density.