gorge historically known as the Sawtooth Gorge before opening to a narrow coastal plain. It then meanders back to the southwest along the eastern flank of the Seaward Kaikōuras as a braided river for around before turning once more to the southeast and emptying into the Pacific Ocean. In total, the river has a length of roughly , making it the 8th longest river in New Zealand. Northern tributaries along the middle segment of the Clarence River (e.g., Mead Stream, Dee Stream, Branch Stream, Muzzle Stream) cut through an uplifted, folded and rotated block of limestone and marl that accumulated on the seafloor from the late Cretaceous through the Paleocene and middle Eocene (75–45 million years ago). Exposures of this limestone—the Amuri Limestone—provide some of the most complete records for this time interval of Earth's history. They have provided important insights to our understanding of the Paleocene-Eocene Thermal Maximum (PETM), Eocene Thermal Maximum 2 (ETM-2), and other Paleogene hyperthermal events. The geography of the Clarence is also affected by New Zealand's frequent earthquakes. In the aftermath of the 2016 Kaikōura earthquake, a slip blocked the Clarence River from its mouth, causing a buildup of water behind it. Due to the risk of flash flooding downstream, residents below the slip were evacuated. The river broke through the debris 16 hours after it occurred. Notes References Rivers of the Marlborough Region Rivers of Canterbury, New Zealand Rivers of New Zealand