The Central Plateau has probably been a land mass ever since this period, but the rest of the country was flooded by the Palaeozoic sea.
The land mass of Australia rises to a mean height much less than that of any other continent; and the chief mountain systems are parallel to, and not far from, the coast-line.
South America and North America follow this type most closely; Eurasia (the land mass of Europe and Asia) comes next, while Africa and Australia are farther removed from the type, and the structure of Antarctica and Greenland is unknown.
It is interesting to observe, as will be shown later, that during the Mesozoic era there was a land-mass in the north of Asia and another in the south, and between them lay the sea in which ordinary marine sediments were deposited.
The northern land-mass has been named Angaraland by E.