Dating methodology for the Vishnu Schist

Before I begin, I would just like to point out that, whilst I am a devout Roman Catholic, I am having many troubles as to which creation theory (Creation or Evolution) I believe. Suffice to say I have seen much evidence for and against both, but I am certainly open to more evidence either way.I have a particular question about carbon dating...Many supporters of the 'Young Earth' theory accuse carbon dating techniques to be flawed. I myself have seen evidence for it, but fear it to be the rampant criticism of some of my fellow close-minded Christians. And so, I was hoping that a discussion may help me with my conclusion...A very simple thing that a mate of mine (not the birghtest fellow in the world, but certainly logical) exposed to me, was this:This 'evidence' concerns the Grand Canyon (as many of you Americans would be familiar with).The Vishnu Schist, lying at the bottom of Inner Gorge, is said to be up to 2 billion years old. Now, the deepest point of the Grand Canyon is approximately 6,000ft or 1800m. Now, according to my limited understanding of geology, greater depth implies greater age, no? But, doing the math (and this is also assuming the Vishnu Schist is at the bottom of the Grand Canyon, as it may very well not be), this essentially means that every 1.8 micro metres is a year!Now, a simple dust storm could cover centimetres of the top (at this point), no? And of course, a dust storm does not happen over 20 millenia! I know this is putting it extremely simply, but it was just an example I was given by a 15 year old fellow, and it makes sense.Once again I am no geologist, so of course, I am not convinced. I am well open and prepared for complete and utter destruction of this example; just be aware that I'm eager to read it. I started this topic to learnWhich forum? Origin of Life I guess...Edited by Centrus, : No reason given.

Thankyou everyone for such explanatory replies, they were extremely helpful.I apologise for my misunderstanding... it obviously shows how little I know of geology. I was interested in both subjects; that of carbon dating and that of the explanation of the Vishnu Schist. As for this particular thread, I juts thought it easier to concentrate on my example supplied. Your explanations were wonderful, but they still leave me with a question...If the accumulation is indeed an average, taking into account the additions and subtractions made (which makes perfect sense), how is it possible for us to age? How do we know when these particular additions/subtractions occurred? Or how much rock/sand was added/subtracted? Or how long the gaps of time in between were?