All can be used to make a new scientific law .
Red and white blood cells are produced in bone marrow.
Answer: Chemical reactions occur when chemical bonds between atoms are formed or broken. The substances that go into a chemical reaction are called the reactants, and the substances produced at the end of the reaction are known as the products.
Explanation:
Because the rock is laid down over time, the oldest rock (and fossils or whatever) will be in the lowest layer. As you go up, the age decreases - you are looking at younger rocks.
This doesn't tell you the *absolute* age of the rocks - you can't say from this evidence whether they are 100 million or 500 million years old. But you can see changes over history and you can get an ordering in time.
