The excursion to the Old Boolcoomata region of the Olary Domain, Curnamona Province, in South Australia presents most of the stratigraphy of the late Palaeoproterozoic Willyama Supergroup and evidence for its complex deformation during the ~1600 Ma Olarian Orogeny. The Curnamona Group is characterised by extensive albitisation of its dominantly psammitic and psammopelitic metasediments and intercalated felsic volcanics of the Abminga Subsuite, deposited in a rift basin at ~1720–1710 Ma. It was intruded by syn-rift A-type granite of the Ameroo Subsuite at ~1710 Ma. The Saltbush Group disconformably overlies the Curnamona Group, commencing with quartzite, psammite, calc-silicate and sulphidic metasiltstone of the Bimba Formation and overlying volcaniclastic Plumbago Formation (~1697 Ma), together comprising the Larry Macs Subgroup. This passes up into the dominantly pelitic Raven Hill Subgroup which contains exhalative quartz-garnet lenses similar to those in the broadly equivalent Broken Hill Group of the Broken Hill Domain. The Raven Hill Subgroup is the youngest unit intruded by the mafic Lady Louise Suite (~1685 Ma), coeval with mafic sills and dykes in the Broken Hill Domain. The Olarian Orogeny involved large-scale nappe stacking, thrusting and non-cylindrical folding. Deformation was probably continuous and progressive with overall north-west directed tectonic transport under amphibolite facies conditions, although metamorphic grade generally decreases to the north. The excursion area contains belts of different grade: the Outalpa Subdomain is lower amphibolite facies while the Bulloo Subdomain is mid- to upper amphibolite, accompanied by extensive migmatisation. S-type granites of the Bimbowrie Suite intruded late in the Olarian Orogeny, and are themselves in places deformed by the network of early Mesoproterozoic greenschist-facies shear zones that criss-cross the Curnamona Province, some of which were re-activated in the Cambrian Delamerian Orogeny.