Question

What are fossils?how do we know how old the fossil are?

Answer 1

A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells etc.

Scientists combine several well-tested techniques to find out the ages of fossils. The most important are Relative Dating, in which fossils and layers of rock are placed in order from older to younger, and Radiometric Dating, which allows the actual ages of certain types of rock to be calculated.

Answer 2

Those substances gives produce a large amount of heat and light energy are known as fossils fuel.