Preface to the special issue of Precambrian Research on the understanding of gneiss complexes, in honour of Clark R.L. Friend

Gneiss complexes are the world’s most horrendously complexrocks to understand (see cover of this issue), yet they form a largeamount of the continents, albeit they are normally hidden fromview by sedimentary sequences. The last half century has seenenormous advances in understanding these rocks, which form notonly a large amount of the continental crust, but also hold much ofEarth’s oldest rock record – the Archaean.