How do geologist know what they are looking at really is what they say it is?

And these different types are recognizable and each results from a different history and process?Do the different types point to different initial origins or only to the formation process?

Yes. Ultimate and proximate analyses do it very efficiently. Classification. Yes and no. Yes and no. No. Lots of different processes.I don't really understand why anyone would think that there's only one process involved in the formation of any rock.Edited by Pressie, : No reason given.Edited by Pressie, : No reason given.

If we look at the different "coal" types as presented (peat to lignite, to bituminous to anthracite and eventually to graphite), what would be the original landscape that resulted in each final product and that process paths are involved in each?Is part of the answer related to where in a series of processes the sample has completed?

"The" original landscape? There's not one 'original' landscape. Lots of different landscapes.

Okay, but then can you walk us through the cycle from some surface landscape to each of the resulting coal types?

Just to elaborate a little on Pressie's responses... Yes, in fact a child could recognize the differences. However, there is a whole science behind coal analysis at the analytical level. The degree of process is the most important factor. But again, it's not just simple burial, but other factors can contribute such as deformation. They can, but the primary difference is in the degree of post-burial processes.When I went to school, there were entire laboratories dedicated to the detailed study of coal and numerous PhD's were cranked out over the years. This is not a trivial topic no matter how YECs present it.

Any time you can accumulate a pure organic sediment, you can ultimate end up with a coal bed.Here is a peat deposit in the bogs of Northern Ireland. There is almost no input of clastic material at this lcoation, just an ages long build up of organic debris. Even the streams in this immediate area have no rocks, sand, boulders, etc.Just dead grasses, some animals and (once upon a time) trees and roots.This material is, even today, harvested and used as fuel. In fact, that's why scotch tastes the smokey way it does.Interestingly, there is sheep skull in the picture. While it is younger than the peat itself, geologically speaking, it is of the same age. With very little imagination, one could see it being buried eventually and become part of the geological record. However, since we see erosion occurring here, it's not too likely in this case.Certainly, you can imagine other depositional settings, such as swamps or ponds. I understand that there are even some Precambrian coal deposits, though I'm not really sure how they formed, but basically, it's just 'pure' organic carbon residue.

Great information.So in the Mad tradition of spy vs spy can we make a general statement that the various forms of coal products are more the result of processing than original source. All begin as marshy wetlands that remain marshy wetlands long enough for deep deposits of dead plant material to accumulate?And for the other Spy, can we say chalk results from long term deposition of dead micro-organisms with calcite shells in moderately deep water while other forms of limestone result from different original environments?

As a general rule.

Not really. The processes are similar, but the original sources provide different products. In some circumstances leaves tend to be preserved better than branches to form coals later even undergoing similar processes.In other circumstances branches tend to be preserved to form coal later. They produce different coal products.Then there's also the bark and stuff like that; which also play a role.Then also the species of plants growing, dying and getting preserved also play a role. Then depth of burial and modes of preservation and proximity to inflowing inorganic sources. etc. That's why Gondwana coals (Africa, Australia, India) differ so much in everything from northern hemisphere coals. Different plants, different time periods, different outcomes eventually.Similar processes, though.Gondwana anthracites have completely different properties than northern hemisphere anthracites, for example. The processes are similar, yet the original sources differ.

So when the various types of coal that have been mentioned (peat to lignite, to bituminous to anthracite and eventually to graphite) so far are being considered... ... which products or product would get produced in each situation; or. are you saying the the characteristics of bituminous coal (as one example) is different in the situations you mention. Is it a matter of specific chemical composition varying by source material?

I'd like to take a short side trip simply to satisfy a question that has haunted me since it was first brought to my attention many many moons ago.The Rock of Gibraltar is a massive limestone deposit but strangely it seems to be upside down with the oldest rocks at the top and the youngest near the bottom.?????????????What is that story? How was that determined?

It's the remains of part of a great big overturned fold. Here's a smaller one so you can see what's happening.

But how was it determined that things were overturned?

Remembering back to something I read two or three decades ago, that is determined by the orientation of fossils and ephemeral markings contained within. There are a number of things that can only be buried top-side-up, so when you find them top-side-down then that would be an indication. Examples would include ripples on stream and lake/sea bottoms, animal tracks, plant root systems, animal burrows on the sea bottom. I seem to recall that trilobites normally get buried right-side-up.The rock layers themselves can also offer evidence. Just that the layers are in the reverse order that you would expect from everywhere else they occur would be a clue that something may have happened. And layers that were formed by rapid depositation (ie, in a single depositation event) would be expected to exhibit a "peanut jar" distribution of materials with the larger particles on the bottom of the layer, since they would have settled out first, and graduating up to the finer particles which would have settled out last -- ie, actual hydrodynamic sorting. If you find a layer where that order is reversed, then that would be another clue. Or the upper surface of a surface lava flow oriented downwards. Etc.Of course, you should verify all of that. As I said, I remember having read about that several years ago.