Coal is the remains of [?] that grew and decayed in [?] areas of the earth. The remains were [?] by the weight of material above which squeezed out the [?] content and changed the vegetation into first [?] and then finally coal.

As it aged the water content [?] and the [?] content increased. This means that with age the [?] of the coal improves. The best type of coal found in NZ is called [?]. This process however takes [?] of years to occur.

[?] activity is then needed to bring these coal [?] to the surface where they are more [?] and able to be mined.