Question

how are high and low island formed

Answer 1

high islands are basically volcanic islands and low islands are the sedimentary islands so high islands form by accumulation of lava whereas low islands form by accumulation of sediments

Answer 2

Basically, the high islands are volcanic islands where as the low islands are the sedimentary islands.

So the high islands are formed due to the accomudatiom of the volcanic lava and the low island s are formed due to the decomposition of the sediments.