I rely on Benton for some technical stuff. I know he has been around his father and other geos. I know he has some knowledge. Why? Your not finished yet?

We would not say "the great sulphide unit is a massive marker horizon for ......

Where is the rest of the sentence????

Now let me give you an example of how Geos use the term. Better still, I'll show you how they use the term:

Just go to today's 2nd nr and read. You will then see how Geos use this term you are so hung up on....Don