Complex sentence: Little is known about the Norfolk Ridge; however, it is about 2000 m below sea level, is Late Cretaceous in age and is part of Zealandia, a submerged continent that sank 60-85 million years ago.
Split into simpler sentences: Little is known about the Norfolk Ridge; however, it generally lies about 2000 m below sea level and consists of Late Cretaceous continental crust. It is part of Zealandia, a submerged continent that sank 60-85 million years ago.