Fault blocks are very large blocks of rock, sometimes hundreds of kilometers in extent, created by
tectonic and localized stresses in the
Earth's crust. Large areas of bedrock are broken up into blocks by
faults. Blocks are characterized by relatively uniform
lithology. The largest of these fault blocks are called
crustal blocks. Large crustal blocks broken off from tectonic plates are called
terranes. Those terranes which are the full thickness of the lithosphere are called microplates. Continent-sized blocks are called variously
microcontinents, continental ribbons, H-blocks, extensional allochthons and outer highs.