A Late Miocene to Pliocene/Lower Pleistocene sedimentary sequence is located 3–15 km west of the New Zealand Alpine Fault and north-west of Lewis Pass.Rappahannock Groupis non-marine, and formations are based on the pebble content of conglomerates which are interbedded with sandstones and carbonaceous siltstones. Evidence for the timing of transcurrent movement on the Alpine Fault is provided by provenance studies of pebbles in these conglomerates. The basalFrog Flat Formationand overlyingSpargo Formationcontain conglomerates with 58-87% arenite pebbles. These arenite pebbles are characterised mainly by a quartz modal count of generally < 10 and are thought to be of Caples/Pelorus origin. Pelorus rocks on the western side of the Alpine Fault, north of Rappahannock Group, are rejected as the arenite source area as there is no evidence of Pelorus pebble transportation south to the Rappahannock Group. The Caples terrane is a more probable source area and is thought to have been located across the Alpine Fault adjacent, and to the east of, the depositional basin during the Late Miocene. Approximately 420 km of subsequent dextral shift on the Alpine Fault has resulted in the locating of the Caples terrane in its present position in west Otago/Southland.