# How Deep In the Earth Is Coal Found? **URL:** \ **Category:** Factual Questions\ **Created:** [February 9, 2005, 8:21am UTC](https://boards.straightdope.com/t/how-deep-in-the-earth-is-coal-found/289169 "2005-02-09T08:21:47Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [February 9, 2005, 8:21am UTC](https://boards.straightdope.com/t/how-deep-in-the-earth-is-coal-found/289169/1 "2005-02-09T08:21:47Z")
And, what happens to coal in extremely deep seams? Does the cola get compressed into something different from anthracite coal? And, why are coal seams accompanied by pockets of methane gas? Wouldn’t this eveolved gas have migrated out ages ago? Are fossiles commonly found in coal seams? ---
**Author:** ![MEBuckner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mebuckner/32/2896_2.png) [@MEBuckner](https://boards.straightdope.com/u/MEBuckner)\ **Post date:** [February 9, 2005, 8:53am UTC](https://boards.straightdope.com/t/how-deep-in-the-earth-is-coal-found/289169/2 "2005-02-09T08:53:03Z")
_Postin’ in a coal mine Goin’ down down down Postin’ in a coal mine Whoop! About to slip down Four o’clock in the mornin’…_ **Moderator’s Note:** Slipping on down on over to General Questions. ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [February 9, 2005, 9:20am UTC](https://boards.straightdope.com/t/how-deep-in-the-earth-is-coal-found/289169/3 "2005-02-09T09:20:01Z")
Just a quick answer off the top of my head. > [@ralph124c](#): > > How deep in the earth is Coal found I don’t know that there is a definitive answer to this. Some parts of the earth’s crust that used to be close to sea level and covered in plant life are now way, way underground or under the sea. These places, called subduction zones, could have coal down in them at depths of like 30 or 40 km. I don’t know whether anyone’s looked for it at those kinds of depths. > [@ralph124c](#): > > And, what happens to coal in extremely deep seams? Does the cola get compressed into something different from anthracite coal? The progression from peat to lignite to bituminous coal to anthracite is more related to age than pressure, but I suppose that you might end up with something like a really, really, impure diamond. > [@ralph124c](#): > > And, why are coal seams accompanied by pockets of methane gas? Wouldn’t this eveolved gas have migrated out ages ago? The rock overlying the coal can be pretty much impermeable. > [@ralph124c](#): > > Are fossiles commonly found in coal seams? Yes, usually impressions of the plants that the coal formed from, but ocassionally other things as well, like teeth and shells. ---
**Author:** ![Cazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cazzle/32/75_2.png) [@Cazzle](https://boards.straightdope.com/u/Cazzle)\ **Post date:** [February 9, 2005, 11:45am UTC](https://boards.straightdope.com/t/how-deep-in-the-earth-is-coal-found/289169/4 "2005-02-09T11:45:08Z")
I live in a coal mining region in Australia, the Latrobe Valley. The Powerworks website ([http://www.powerworks.com.au](http://www.powerworks.com.au)) has heaps of info on the formation of the coal, etc, and I found this quote about three screens in: > [@](#): > > The most favourable areas, coal seams ranging in thickness of 60 metres through to 140 metres with an easily removed layer of sand and clay averaging only 15 metres deep were found. Boring at one point found the coal bed, only 27 metres underground to be 270 metres thick! Click [this link](http://www.powerworks.com.au/coal.asp) for more information, though it may be a little too specific to the coal deposits in my region to be very useful to you. ---
**Author:** ![Fuji\_Kitakyusho](https://avatars.discourse-cdn.com/v4/letter/f/f0a364/32.png) [@Fuji\_Kitakyusho](https://boards.straightdope.com/u/Fuji_Kitakyusho)\ **Post date:** [February 9, 2005, 2:17pm UTC](https://boards.straightdope.com/t/how-deep-in-the-earth-is-coal-found/289169/5 "2005-02-09T14:17:10Z")
I work in this industry - primarily in North America. Without exception, coal mining operations here are surface (open pit) mines. As to actual depth of the coal seams, it varies, as does the local topography, but the mine plan generally involves moving the overburden around to expose the coal, and then removing the exposed coal with shovel and truck operations.