Explain the differences between Oceania's high islands and low islands in terms of physical geography.

Because high islands were formed by underwater volcanoes, they tend to have rich volcanic soil. Their terrains are mountainous and rocky. Low islands, which surround lagoons, were formed by connecting coral reefs, or atolls. They are round, small, and flat in shape and often have no source of freshwater.

Because high islands were formed by underwater volcanoes, they tend to have rich volcanic soil. Their terrains are mountainous and rocky. Low islands, which surround lagoons, were formed by connecting coral reefs, or atolls. They are round, small, and flat in shape and often have no source of freshwater.