This excursion guide describes the glacigenic rocks of the Smalfjord and Mortensnes Formations, and parts of the intervening Nyborg Formation, at the base of the Vestertana Group in the Tanafjord-Varangerfjord region of East Finnmark, NorthNorway. These are agreed to be either of glacial (sensu lato) origin or signifi cant to our understanding of Neoproterozoic glacial processes and events. The Smalfjord and Mortensnes Formations have been equated with the Marinoan (636.3 ± 4.9 Ma and 635.5 ± 1.2 Ma) and Gaskiers (584-582 Ma) glaciations, respectively. The rocks, which are superbly exposed, display a wide range of sedimentary lithologies/facies; lodgment, banded, deformation, fl ow, and melt-out diamictites; as well as glaciomarine, proglacial, and fl uvioglacial sediments. Diamictites derived from carbonate units showing the Trezona and Wonoka negative δ 13 C anomalies are seen.Glaciotectonic and/or soft-sediment structures described include folds, normal and thrust faults (imbricate fans), fl anking structures, shear-sense criteria (sigma clasts), striations (with paleoloess), lobate-cuspate contacts, downward intrusion of fl uidized sediments (with bridge structures), pro-and subglacial channels, nested channels, graded beds, possible iceberg dump structures, ghost clasts, dropstones and lonestones, allochthonous rafts of substrate sediments, ball-and-pillow structures, convolute laminations (pseudonodules), delta foresets, ice-crystal molds, sandstone dikes, and a possible kettle hole. The complex geometry of the sub-Smalfjord unconformity onto older Neoproterozoic sediments and the Archean Baltic Shield is documented at several scales. Marinoan cap dolostones (Maieberg negative δ 13 C anomaly), with typical sheet cracking (and "pseudostromatolites") and atypical clastic interbeds, are described from the base of the Nyborg Formation at several localities.