The Basin continued to fill with sediment from the ice-covered mountains.  Large braided rivers like the Rakaia River in NZ (opposite) deposited deep layers of rounded pebbles and rocks to form the thick layers of conglomerate rock that we see in the cliffs and rock platforms.

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The sea level rose and fell. When it was steady, large swamps formed on the plains between the river channels. Trees called Glossopteris, similar to today’s mangroves, as well as many different ferns and mosses, grew in the swamps and produced layers of humus that did not decay or decayed little in the boggy swamps. 

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These peat bogs became today’s coal seams.  10 m of  bog was compacted into 1 m of coal and some of the coal seams are 8m or more, thick.