Glacial geomorphology of the Ahuriri River valley, central Southern Alps, New Zealand

Detailed geomorphological mapping of ice-related and post-glacial landforms is widely used to explain past glacial fluctuations and dynamics. Here we present the first detailed glacial geomorphological description of the landform assemblages produced by the former Ahuriri Glacier, Southern Alps, New Zealand (44° 15′ S, 169° 36′ E). The Southern Alps of New Zealand experienced multiple episodes of glaciation during the Late Quaternary with large mountain glaciers in many valleys, but very little is known about the Ahuriri River valley, one of the main tributaries of the Waitaki River. We selected a region extending approximately 45 km downstream from the headwaters of the Ahuriri River covering an area of about 532 km2. Our goal was to create a detailed 1:38,000 scale glacial geomorphological map of this area and provide a geomorphological context to support future geochronological work. Glacial geomorphological mapping was performed by combining several field investigations and remote sensing surveys. We provided high-resolution spatial information for all the glacial-related landforms shown on the map (see main Map). The distribution of post-glacial landforms in the middle and lower section of the main valley outline at least three advances or stillstand phases of past glaciers and suggesting the maximum length (∼41 km) of the former glacier during the Last Glacial Maximum. Most of the tributary valleys were also probably covered by ice at this time. Other prominent but smaller size moraine landforms, mostly in the tributary river valleys, also suggest relatively small, post-glacial advance phases of former glaciers.