[3] The basement is of Utsira High is composed of granite that formed in Ordovician times.
[1] Parts of these granites contain saprolite and saprock that formed from weathering above sea level during the Early Mesozoic.
[2] before they became buried in Late Jurassic and Early Cretaceous-aged sandstone.
[1] These weathered rocks may be unconventional petroleum reservoirs.
[2] The strandflat at Bømlo island is considered a sedimentary rock-free equivalent to the Utsira High.