Need Help on the geology side of things.

[Tommtb7]

Hi all, I've been doing a bit of reading on gold in relation to geology lately, I was wondering if anyone could answer a few questions?

From what I've read the majority of gold was found in the upper Devonian layer (roughly 416 million years ago) how do you determine where each layer starts and ends and what are the typical rock types? Are the rock types generally the same through out each layer but are just different ages?

Is there any correlation between the richness of a reef in regards to what layer it's in? It seems the more I read the more confused I get, haha

My local gold feild has old mining records that say they traced the gold down over the jurasic strata then lost it ( they never found the original reef but speculate it could be coming from a small but extremely rich lode above one of the gullies. How would you know when you dig down to the jurasic strata? Would a T. rex jump out and chew of your arm? Lol

 

[Hunting the yellow]

well diffrent layers have diffrent colours for an example sandstone has a creamish colour and slate is jet black now if you whore to go down a mine and saw this as you wore going down it means two massie rock slabs have more over each other and its some times called revirse faulting when one block of rock slides over or becide another if this happens the under side would be in some caces richer in gold then the other and so the molten quartz with the gold flows up it to these cracks as a hydrothermal larva and when it cools its traped for ever untill its found when a mining co find it by drilling holes

heres some more imfo http://en.wikipedia.org/wiki/Hydrothermal_circulation