As well as major contributions to stratigraphy and geological mapping, G. N. Frederiks is particularly remembered for his contributions to the paleontology of the late Paleozoic era (Carboniferous and Permian periods), notably Brachiopoda, Ammonoidea, and Bryozoa.
The Patch reefs from Valle di Rimbianco present a diverse fauna of fossilized calcitic sponges (Porifera), corals (Cnidaria), bivalves and gastropods (Mollusca), Brachiopoda and Echinodermata.