tavan tolgoi's open pit mining photo, page-3

The reason that I am thinking this could be major one is that there is no interruption between seams boundry by foreign materials like smaller sized one(for instance 200-999mt resources one) but similar to Tavan Tolgoi one.

As defination of "Coal is combustable, black sedimentary rock composed predominantly of carbon. It is formed out of plant matter that accumulated at the bottom of swamps millions years age, during the Carboniferous Period" or

"Coal originated from ancient plants that flourished in swamp-like environment millions years ago".

Swamps or swamps-like indicate that usually swamps outer side could be swallow like BTE1(40m) and getting deeper(BTE2) towards centre.

Rregards,