In the Alps and Apennines Steinmann defined what later became known as Steinmann's Trinity, the occurrence of serpentine, pillow lava, and chert. The recognition of Steinmann's Trinity served years later to build up the theory around seafloor spreading and plate tectonics. Steinmann himself interpreted ophiolites (the Trinity) using the geosyncline concept. His studies of ophiolites in the Apennines paved the way for the discovery of allochthonous nappes in the Alps and Apennines.