So, in our example , after the second life is over (that's 10 years since each half life is 5 years), there will be $$\frac 1 2$$ of $$50\%$$ of the substance left, which, of course is $$25 \%$$.

And the pattern continues, every 5 years another half life reduces the substance by $$\frac 1 2$$, so after the the third life is over ( the 15 year mark), there will be $$\frac 1 2$$ of $$25\%$$ of the substance left , which is $$12.5 \%$$.

Typically, we do not even consider the negative x values because the x-axis typically represents time.

In short, the half life tells us the scale of the graph.

Then the paleontologists use the geologists' dates as evidence for the age of the fossils! The relative order of the strata was first determined by the principles of stratification. Beagle, a very strong Bible believer, made it a point to have a copy of Lyell's book for the ship's library.

(The principle of superposition was recognized as early as 1669 by Steno.) Reverend Benjamin Richardson and Reverend Joseph Townsend were a couple of early geologists involved in this work. Obviously, even Lyell was not pushing evolution at the time.

C) dating usually want to know about the radiometric[1] dating methods that are claimed to give millions and billions of years—carbon dating can only give thousands of years.

People wonder how millions of years could be squeezed into the biblical account of history. Christians, by definition, take the statements of Jesus Christ seriously.

"Either you do the work or you get the credit" Yakov Zel'dovich - Russian Astrophysicist Fortunately it is not always true.They did not have the benefit of cheap, off the shelf, mass produced batteries. Bronze is a relatively hard alloy of copper and tin, better suited for the purpose than the much softer copper enabling improved durability of the weapons and the ability to hold a cutting edge.For many years the telegraph, and later the telephone, industries were the only consumers of batteries in modest volumes and it wasn't until the twentieth century that new applications created the demand that made the battery a commodity item. The use of bronze for tools and weapons gradually spread to the rest of the World until it was eventually superceded by the much harder iron.So, we have a “clock” which starts ticking the moment something dies.Obviously, this works only for things which were once living.

By 1830 Lyell's famous textbook, Principles of Geology, came out. Such was the age of the great creationist geologists!