The Pongaroa Fault is a strongly curved, but overall north-east-trending structure. Considerable Miocene movement on the fault is indicated to the south of Pongaroa township, where it juxtaposes dissimilar pre-Taranaki successions. At its southern end the fault dies out on the surface in beds of Taranaki age; however, construction of a paleogeological map shows that it continues southwards, concealed beneath Lillburnian-Waiauan and Taranaki rocks, to join the Tinui Fault. Comparison of the paleogeology on the north-west side of the Pongaroa Fault, 3 miles south of Pongaroa township, with the paleogeology in the south-east of the mapped area, reveals that the successions were originally contiguous and that they were displaced during the Miocene by about 8 miles of dextral transcurrent movement on the Pongaroa Fault. After deposition of the Lillburnian-Waiauan and Taranaki, minor transcurrent movement on a north-east-trending cross fault offset the Pongaroa Fault.