Abstract
The hills around Benmore Darn are formed of complexly-deformed, metasediments of the Torlesse Supergroup. These include a narrow, 130-m-thick sliver of schists and meta-siltstone of Permian age, called the Akatarawa Formation (new name). This formation includes a marker bed of fossiliferous limestone, limestone breccia and ferruginized volcanics, deposited in a quiet, open marine shelf environment, and in warm temperate to tropical water termperatures.